have you logged into the game since? Change your password for that game. apparently the udid can be used to log into someones account if you check the save password box?
the relevant part:
"Your question was not answered, Ex: If you were to now give me your UDID & you owned the app SevenSwords. I could log into your acc due to you having checked "Save password" On the square box before log in (As so everyone does). If any other apps asked if you wanted your password saved (on the devices UDID), it would be saved to it, meaning if I got a hold of it & downloaded the app on an iPod/iPhone/iPad, I would have your password saved on that UDID, allowing me to do as I please (Deleting your acc or worse, saying things you would normally not say). Now that is not me & I would never do such. I consider only giving it out if you are a beta tester."