The same thing happened to me. I was using just a plain Sales Lander, no ads. Then suddenly I received an e-mail that I was blocked by Google. I can't see any reason why this would happen.
But anyway, I asked the support "What does it have to do with my simple Sales Lander? I don't need ads", and they replied something like we don't know, we don't care, go talk to Google about it. Awesome. Talk about what? I found their move irritating and unrespectful, blocking for no reason without any explanation.
Just switched to Dan now. Looks like Sedo ain't do well for most domainers here, and they are making things even worse by providing such negative experiences for their sellers. Probably not wise.