I don't rely on the airlock to tell me if it is fermenting. I am used to seeing the bubbles, however. I have had a batch or 2 that didn't bubble. If there are no bubbles after a few days, take a hydro reading. You'll almost always find it was fermenting, unless you had a serious problem (like dead yeast, no aeration, etc). The bubbler is a toy, for the most part. It looks cool, but not reliable.
In the immortal words of Mr Popeil: "Set it and forget it". The yeast know what they're doing. Oh, and don't forget RDWHAHB!
How did it turn out?