Game Center keeps asking for password since a couple of weeks?

Is it only me, or is it happening to you to? Game center, since last 2-3 weeks, keep asking for password, when I play a game that relies on it. example: letterpress. I never had a problem with this, but now everyday, I need to supply the password.

it does work correctly after that, its just that this password thing keeps popping up.

doesn't seem to be a local/device problem since any amount of off/on or restore doesn't help.