I went back and watched the sex scene in "Now What?" House actually has his watch off toward the end of the sex scene; he seems to be wearing it when he places Cuddy on the bed and then we can't see it for awhile during the sex...but then when there is a scene of Cuddy on top of House...he isn't wearing the watch. I had initially thought that he hadn't removed it until the next day...so I wonder if the fact that it is on during part of the sex scene is significant in anyway.