@Background Pony #DD0F
The way I see it they didn’t just discover their cutie marks, they decided that “this is who we are” and their magic reacted to it. Also the fact that they are three friends who decided to stick together might have something to do with it considering the whole friendship is magic thing Equestrian magic has going.
@ProjectRKA
That wouldn’t account for it. Scootaloo is in the exact same position. If the camera was looking from a different angle she’d be in a different place too.