I bought a U2 signed Numb vhs video about 10 years ago for an auction that was supposedly for Amnesty International. I looked at it years later and realized how awful the forgeries were. I mean REAlLY bad, lol.
Everything from the GRAMMY Foundation should be signed for them, usually in their presence, and absolutely authentic. They don't run their auctions on regular eBay...they run them on their private sale platforms.
It's a great charity and I'd hate to see them blamed for something not their fault. They're one of the small number of charity auctions that has authentic music.
But sadly, everyone's right about your U2 drumhead. It's definitely not genuine.