"Suspicious Activity"...

I tried to sign on today and i was greeted with a message that told me that my battle.net account was locked due to "suspicious activity". While that is extremely vague, I have not been able to figure out what that suspicious activity was.
I restored my account using email password reset, and immediately logged on to check my characters and I looked over every one and there is not a single thing missing or changed.
I then opened a ticket and eventually got the privilege of speaking with a GM. I asked the GM what this supposed "suspicious activity" was but he was unable to tell me.
Also, something that may be of some significance, during my whole waiting process for the ticket to reach a GM, I received an in-game mail from "The Postmaster" containing 2x Emblem of Frost. The GM I spoke to however said that this was because at some point I didn't get the Emblems I deserved from a dungeon. So in other words, it was unrelated to this "suspicious activity".

After speaking to the GM I logged out, and then a few hours later I logged back in or at least attempted to. I was met with the same message about "suspicious activity". I feel now that if I reset my password again, my account will just be locked again.

I guess my overall question is 'What constitutes as "suspicious activity"'?
And if a blue happens across this.. what did I do that is so "suspicious"?