Are you sure that he didn't leave behind any of his buddies?
Be careful ... once they get in ... they often come right back!
Long story short ... I had one a few years ago ... tore open a screen in the window. It just takes a wee slit. I replaced it with animal proof screening. Though a couple of days later ... he found another window with the regular screening. I was lucky that I knew soon enough, and was able to get him out fast enough each time, without any damage! Whew!