Call me naive, but I REALLY think people are overreacting on this. Yes, the timing does seem quite coincidental given the Cloudflare bug, but Google has a pretty good record of being transparent with these things.

On top of this, Google does not use Cloudflare and as far as I know there have been no reports of accounts actually being comprised, only logged out. I would wager whatever maintenance routine they were carrying out accidentally invalided some user sessions.