If you monitor your home oven, you'll notice the same swings in temperature. You preheat the oven, the elements seek to keep that temperature. It drove me crazy the first time I monitored the Cookshack, but I think it's something I just took for granted in my home oven. I wouldn't worry about it unless you see a huge swing, over 75 degrees, or the smoker doesn't compensate by dropping. It's a good thing to monitor. Keeping records helps a lot.
Peggy