If it's plagiarism (which is most likely the case), you don't get a warning before you're banned.  You're responsible for reading the forum rules before you start posting, and copy/pasting material from other sources without citing them is one of the rules.  You aren't being banned for being a part of any specific signature campaign, and as the ban PM stated, you got banned either for plagiarism or spamming.  Since members generally aren't banned for spamming--it has to be really bad before that happens--most likely you copied something from elsewhere and didn't give an indication where it was from.

Bitching about not getting a warning is going to fall on deaf ears here.  Even though there's a rule on bitcointalk dealing with it, people ought to know better than to steal someone else's words/thoughts/work.  No warning is necessary.