I brewed a wheat a couple of weeks ago that only bubbled for a few days, before it settled down to one bubble every ten minutes or so, and eventually to nothing. So it's probably nothing to worry about -- you may have just had a few days of really active fermentation.
Extra tip: I read somewhere (Palmer's book, probably) that you should fill the airlock with vodka or sanitizer instead of water, to prevent contamination in case of backflow. I use Starsan (food safe at normal concentrations), and fill the airlock with that. The only downside is that with a super-active fermentation, all of the Starsan will bubble away. I need to pick up some vodka.