Game Center login required daily

Since the last update, my iPhone 5 is asking me to connect to the Game Center (logging on and going through the 2-step verification) every day. It doesn't matter which game I play, if I open one I have to go through the process. Prior to 8.4, I connected once and was never bothered with it again. I've not heard anyone else having this issue, so is something wrong with my phone?