It's funny to hear this experience. I've been doing this consistently for about 5 years now and have noticed 2 instances where this occurred, and in both there were prior disclosures about a security failure.

I tend to sign up for a lot of things (I'm seeing over 150 unique email addresses I receive emails from using this scheme), but I guess I'm just getting lucky.

Also, just out of curiosity, where does one sell email addresses, and how much are they worth? I take signups on a few websites, and I'd never sell my users' email, but I'm just curious to learn more.