I purchased from StubHub four lower level, sideline tickets to the Peach Bowl. I printed the tickets, and considered it a done deal. Several days later (the morning of the game), I received an email and a call from StubHub telling me that the seller of the tickets claims that he cancelled the listing, and was refusing to part with the tickets. StubHub offered to replace the tickets with four lower level tickets in the CORNER. I pulled up the StubHub website while I was speaking with the stubHub representative, and I pointed out that they had four sideline (not corner) tickets that were available in another section. StubHub refused to replace my tickets with the other sideline tickets. The StubHub representative explained that StubHub is merely a broker, and that StubHub does not carry an inventory of tickets. StubHub gave me four replacement tickets in the corner, and refunded a small portion of the purchase price.
The take away -- you, too, could receive a call from StubHub on Gameday telling you that your tickets are not valid.