Is Facebook bleeding users in the U.S.? A recent report claims that Facebook—while still seeing meteoric growth worldwide—managed to lose about 6 million “active” U.S. users in May. That would represent Facebook’s first stateside user slump in a year.

So, has the U.S. finally had enough of Facebook? Depends on who you ask, of course.

The new Facebook figures (which also saw drops in “active” Facebook users in Canada, the U.K., Norway, and Russia, but growth in smaller countries “late in adopting Facebook”) come from Inside Facebook Gold, a site that tracks Facebook activity based on data supplied by the social network’s advertising tool. In other words, we’re talking estimates, not exact figures from Facebook HQ.

Indeed, the Inside Facebook blog admits that its numbers can be “buggy, delayed, or otherwise unclear,” while noting that ComScore, a competing tracking tool that doesn’t rely on Facebook’s ad tool, reports that the social networking giant actually gained about 3 million U.S. users in May. Meanwhile, other tracking sites are still compiling their May usage figures for Facebook, according to Inside Facebook.

Facebook itself was quick to dismiss Inside Facebook’s findings, telling the Financial Times:

From time to time, we see stories about Facebook losing users in some regions. Some of these reports use data extracted from our advertising tool, which provides broad estimates on the reach of Facebook ads and isn’t designed to be a source for tracking the overall growth of Facebook. We are very pleased with our growth and with the way people are engaged with Facebook. More than 50 per cent of our active users log on to Facebook in any given day.

Of course, we shouldn’t be surprised to be getting spin from Facebook’s PR department. But as the Financial Times wisely notes, we’re only looking at “a couple of months’ data” here:

This is not the first time that people have tried to suggest Facebook is losing momentum – and each of them has, so far, proven a blip in an otherwise frenetic growth rate.

here’s the thing: Facebook’s crazy-fast growth is sure to start slowing sooner or later, but it’s too soon to tell if “sooner or later” means “now.”

Source: Inside Facebook, Financial Times