I've had two readers block me when I hadn't even ever read with them. Some people block anyone who's ever left negative feedback, some people block new accounts that haven't left any feedback yet at all. It's hard to understand and I think not very good customer service. I was so confused the first time it happened, with a reader I had never even read with yet, I called customer service and even they admitted it was not a good way to conduct business. But he said there really wasn't anything they could do about it.
I'm sorry, though, it really sucks when that happens.