Originally Posted by The Boy Scout
He has super speed. No matter where his suit is, he can get to it, change into it, and get back to where he was before anyone can even blink.
I got the feeling that Kryptonian "superspeed" was heavily dialed back for Man of Steel. I don't think we'll be seeing the "in-the-blink-of-an-eye" sort of movement from Superman in this continuity.
Not that I expect the tshirt to ever actually be used, of course, but I just don't think we'll be seeing Clark SUPERSPEED away to the Fortress of Solitude, change into the Superman costume, and return all in less than a second.