>>after that, they never have.

How many times did you quit and rejoin Google?

They asked for mine, rather early in the interview process I might add, in 2008 or so. I politely declined.

If I might ask, how did you go about declining, and what was their response?

Hard to say, I ended up finding funding for a project while I was in the process with them. We never really finished.

Would they expect your grades to change?

A good point; I never joined Google the first time around. I simply assumed that that data would have been discarded. It is quite possible, they have all that data in their system every time they call me for interviews or whatever.