WP's last a month until they expire. Once you've accumulated 10 points you get banned for a month, but that doesn't mean ALL the warnings you received which caused the banning in the first place will be gone once you get back.
For example I have a warning (A 2pt warning instead of a 1pt warning) from the night I was banned (3/4/12) that doesn't expire until 5/4/12. The life of the warning is dependent on how many points you receive, but it's all still 1 month each. I got a 2pt warning which means that specific warning won't expire until 2 months have elapsed, it's the same way for 1pt warnings.
