Good info above!!!
When the heat in the smoker reaches the set temp, it shuts off. However the heat will continue to rise for awhile, especially after a long run upward, and a little more in the Summer. I've had mine hit 300* already. It will settle down when it cycles a few short distances.
By the same token, when the temp in the smoker gets 2* below your setting, the element will come on, but the heat in the smoker will continue to drop until the element is on long enough to catch up. This drop is a bit worse in the Winter. You may have it set for 230*, the element will come on at 228*, but the smoker temp will get to 215* before it starts to rise again.
None of this is anything to worry about---It's just the nature of the beast.
Bear