have you done another dry run with the smoker to see if there are any issues with your controller?
if it wasn't going above 250 was the element staying on the whole time?
I had an issue with my controller where the house tempo reading wouldn't go over 225 or 250 and as a result it kept the power to the element on for a few hours, never cycling off. the house temp was actually closer to 450f.
found a kink in the temp probe, I haven't replaced it yet or turned the smoker on in months. hope that's all it is. Their help desk said its likely a faulty temp probe.