If Snap’s earnings today are any guide, the digital advertising sector had a booming first quarter. Snap continued a streak of robust results by reporting 66% higher revenue and, for the first time, generating real cash. The top line increase, which was better than Snap had projected, marked the third quarter in a row where Snap’s revenue growth has accelerated.

While investors will be pleased with how Evan Spiegel is steering the ship, one warning sign can be seen bobbing around in the waters. Snap’s North American user growth has slowed over the past few quarters to 5%, half what it was a year ago. It also slowed in Europe, though not by as much, yet it is speeding up everywhere else. Snap’s headline number of 22% user growth wasn’t, therefore, as good as it looked.