Someone called AppleCare under my AppleID, and opened a ticket. What do I do?

I got an email this afternoon asking me to participate in a survey regarding my last call with AppleCare. It gave me the rep's name and the case ID. I assumed it was spam but thought I'd check anyway. I put the case ID into the support system along with my email and voila the ticket is real.

First thing I did was change my password. Then I checked the credit card associated with my account and there are no bogus charges. So now I'm wondering, what's this all about and if there's anything I need to do.

Not sure if this actually has any implications on me other than my account security, so I'm asking here. Perhaps someone else has had a similar experience?