That is a fine looking Gehrig. Very well centered. I see some corner wear and edge wear, but I don't see any creases. It looks like it could have easily been a 4. Go for it, Joey!
Hate to disagree, but it sure seems like there is at least a wrinkle on the card back (from the "Co." in Goudey Card Co. and over the "Boston" all the way to the edge. Also looks like there is paper loss on the back (by the "W" at the start of the 2nd paragraph).
If you do end up buying it, I would keep it in that holder. IMO, there is no way it would get a 50 - and you would be lucky to get a 40.