I'd say an unhealthy (for you) conjunction of signature campaign, recently bought account, hardly substantial posting and a crack down on sig spam will probably be your reason.
Yes it might have been if I was spamming. I have legit posts, and I mostly only post on weekends, as I work on the rest of the days and don't really spend much time on the forum. I was not given a reason yet, so I am not sure it is spamming or something else the reason behind ban. Can moderator clear it up ?