Thanks for all the advice! I think I might just be having a bit of newbie paranoia as I've only done 5 or so cooks. Maybe I just need to leave it be and only worry if it stays at 300 or higher for a sustained period of time (>1hour).
Speaking of patience, the cooking temp dropped to 250 about 35 mins ago and its been there ever since (with 2 closed and 3rd 1/8 of the way open). So maybe the couple hours at 275-285 was just a spike?
also, the last time i didn't evenly spread out my starter coals and just put them in the middle I had a large ring of unlit coals around the outside at the end of the cook as they never lit. that was the only time I've not spread them out and incidentally the only time I've had problems with keeping the temp up.