Traffic & posts go up and down. Holidays are probably part of it. (I was gone for 10 days! )
The contest might have had an effect, but it's hard to say how much. Believe it or not, the daily hits on the site have been busier in the last 2 weeks (after the end of the contest) than they were in the 2 weeks leading up to the draw date. Hits don't = posts though.