Someone made a deposit to my Kraken account

Just got an email from Kraken:

A deposit has been made to your Kraken account.
To see the deposit, sign in to your account and go to the Funding page.

Nobody knows my address, it was never shared publicly, the account has been idle for at least a year, just holding some coins I bought years ago. I won't be home for the next few days, so I can't access the account to check what was actually deposited or where it came from. Has this happened to anyone before, how is this even possible, would I not need to generate some sort of a deposit address first?