It could be Apple is testing the new shipment of iPad 3 with iOS 6. iOS 6 is scheduled at WWDC in June, my guess is iOS 6 will be a refinement of iOS 5 just like Mountain Lion is a refinement of Lion. And there will be a few new things in iOS 6/Mountain Lion not reveal to public yet. Question is will Apple surprise all by giving us a preview of iOS 6 next week?

My conspiracy theory: Apple is pushing yearly iOS update to put further pressure on Android. Apple will be glad that Android 5 will launch later this year, at a time when Android partners are just starting to roll out Android 4 hardware.