Not that I'm complaining...
I think that it's the jogging I've been doing. Not straight on jogging, but interval training on the treadmill at the Y. If you'd like to start a running/jogging routine, begin with interval training.
3 minutes running to 3 minutes cool down/walking. Try it for a few weeks then add more intervals OR more minutes running. Soon, you might find 4 pounds have dropped off of you.