Quote From rewt:
Is it a small journal, in which case it might be due to holidays. I just submitted to a journal and got an auto reply saying to expect delays due to editor absences (only three editors).
The other option is that the two reviewers gave very different decisions and they are quickly asking for a third opinion.
actually it s a very famous well known journal, as i said, the problem is i checked everyday and did not see "under review" step in evoluation.