What does Gandalf mean by “twice now”?

[Alcuin]

As many times as I have read The Hobbit, I have always been a little puzzled by an expression Gandalf uses right at the beginning.

“[F]or your old grandfather Took’s sake, and for the sake of poor Belladonna, I will give you what you asked for.”

“I beg your pardon, I haven’t asked for anything!”

“Yes, you have! Twice now. My pardon. I give it you. In fact I will go so far as to send you on this adventure. …”

What “twice”? I can see lots of times Bilbo slips and hints that he wants to go on an adventure, that his mother’s Tookishness is itching to get through. But I can’t find any two specific things that I can nail down.

How does the ’Moot count “twice”?