I have a standard, non-jailbroken iPhone 4. This morning, randomly, a message popped up asking me to enter my iMessage password. On a PC I would have been suspicious, but Apple have been doing odd things with their security lately, so I responded. Then it asked the same question about Facetime. Ditto.
A few minutes later, entirely by coincidence, I attempted to access my Apple account via iTunes, and my password was not recognised. I reset the password and checked the account – thankfully nothing purchased. Still, this is odd and surely related to the now-suspicious question on my iPhone.
I’ve had a quick Google and seen nothing about this kind of behaviour reported anywhere, but if other people get that prompt and have their password changed, maybe they’ll find this when they search. Another data point.
I don’t know how to tell Apple, and in my previous experience that’s a black hole anyway so I didn’t try very hard.