Are you feeling a draft after the door is shut and the windows are tightly locked? Have you been noticing puddles of water throughout the garage? Are you noticing tiny pieces of chewed up cardboard and other signs of nesting?
Are you starting to become concerned about that odd noise your garage door is making every time you try to open it? Have you also noticed that it's not moving the way it used to- a little more jerky and a lot less smooth?