HI! congrats for your success!!
I've seen the signature of your photo and I also have an autograph from him (I recieved years ago, I can't remember exactly when), but the signature and the writing is clearly different
I don't know if yours is authentic or it's mine but I think the person who signed mine was a different person from the one who signed yours. Here's a photo of mine:
I've been looking in the database other successes and all that I've seen have the same signature than yours, but mine is different

I don't know what happened...