There’s an unfortunately lazy truism in journalism that three is a trend. This is the kind of rule that leads to stories of “EVERYONE QUITTING INSTAGRAM BECAUSE IT WAS PURCHASED,” when really it’s just a couple of whiney loudmouths who wind up rejoining a few days later. Adam Penenberg brilliantly mocked this kind of reporting in his chapter about inconsequential privacy outrages in our Facebook ebook.

Nonetheless, I am about to write a story about only two things happening. It’s not a fact. It may not even be a trend. So let’s just call it a “cautionary heads up.” In the last week, two Facebook execs have quit and left for Pinterest: vice-president of online operations Don Faul and communications exec Barry Schnitt. There are rumors of more.

Before we go further, here’s what this isn’t: A sign that things are way worse than we fear at Facebook or recent bizarre IPO stumbles are in any way causing a sudden exodus of talent. What it may be is the beginning of the unsurprising and inevitable flow of talent away from Facebook to the next hot company du jour in the Valley.

Facebook can do little to fight this — as Google learned years ago and Microsoft learned before Google, cash can only do so much. Google knows. It threw scads of cash at people to stay. Unfortunately that only keeps people who are working for a paycheck. Sometimes those people have mothers in hospitals and 10 children and need a paycheck. More often, they are motivated by money and not cause. That’s not always good for a mission-based tech company.

And Facebook has partially brought this on itself with its permissive use of secondary markets. Much of the staff hasn’t had to wait around for the IPO for liquidity, and it hasn’t. But the pre-IPO mini-exodus didn’t hurt the company much because it was still the go-to company for talented ambitious people who didn’t want to start their own thing. (A rare and dwindling group of people in the Valley’s overheated talent war and angel cash frenzy.)

At some point those people will start leaving. If it’s starting, it’s happening far earlier in Facebook’s public company life than it happened to Google, and that’s likely because of two factors. The first is that Facebook waited longer to go public, and the second is that there are more juicy companies to jump to than there were in the mid-2000s.

No matter the reasons, Facebook needs to do what it can to put this inevitability off as long as possible. The only currency a company like Facebook has is smart people. It’s gone public — Hooray!…sort of – but there’s real concern about its mobile strategy and stagnating revenues.

In fact, the company’s ability to track some of the smartest people in the world is the main reason to be so bullish on it in the wake of a pile-on of negativity and slumping stock. As Y Combinator partner Garry Tan wrote yesterday,

Facebook’s biggest asset is its ability to hire and attract the best talent in the world. This was also what Apple has executed on perfectly since its return to prominence. At both places, there is a strong hacker culture and a true belief that what they’re doing is the most important, society-changing work in the world.

That’s precisely the only cogent argument I’ve seen for Facebook to get into hardware.

Now, does a communications guy and senior operations guy leaving affect a Facebook phone? Of course not. They aren’t engineers. And Mark Zuckerberg excels at hiring, acquiring, and inspiring engineers. But if this is a canary in a coal mine, little news reports like these are important to watch.

To wit: Both Faul and Schnitt followed Sheryl Sandberg from Google. They are precisely the kinds of executives who tend to follow the hot company once it’s getting serious about building a big company. They’re a league above the people who hop between second tier companies hoping for a lottery ticket. They’re the ones who are good at this game. That they’ve hopped Google to Facebook and now to Pinterest is interesting. It’ll be equally interesting to see how many follow.

But one thing is clear: Pinterest should be making utter and total hay on this. If the perception gets out it’s the next hot company — whether these moves are a coincidence or not — that’s invaluable buzz when it comes to stacking your company’s deck to win.