What happened to the perfect game ball?

So what happened to the last game ball of Mark Buehrle's perfect game after first baseman Josh Fields made the final out? ESPN is on the case:

"I found out later I screwed up," Fields said Friday morning on the "Waddle and Silvy" show on ESPN 1000. "I held on to it as long as I possibly could during the celebration after the game, and I think one of the MLB authenticity guys came out and was mugging me down pretty hard and saying 'give me the ball.' And I didn't know that I could say 'no don't take it.'

"So I ended up giving it to him, thinking he was going to put his little authenticity sticker on it and give it back to Buehrle. So as of right now, I guess the MLB has it."

They should give it to Buehrle?