I was in one of the clubs years ago, I thought it was the big central one in PIT, but maybe it was PHL, the place was fairly empty, and spent about 20 minutes being "entertained" by a mouse making it's excursions around the area. I mentioned it to the desk people on the way out, and they were aware of mice in the club. I am also pretty sure there was a thread here about club mice long ago, but I can't seem to find it with search.