I think that's a reference to James's *literal* power of flight, which he's capable of doing at supersonic speeds. Stryfe was dead/not around when Jimmy first discovered he could fly, and might not have been aware of it. But he can fly even faster than he can run, as shown here in the pre-Dawn of X X-Force series where he was shown flying and breaking the sound barrier.
No way! I totally disagree. James developing his own powers is awesome, there was no reason for him to have identical powers to his brother (the Summers and Guthrie siblings all have their own unique powers) and these make him stand out.
Plus, flying "bricks" are fairly rare in the X-world, aside from Rogue and M/Penance.