Did you add wood in previous cooks? Might have been why it was running a bit hot.
Yes, I've used a chunk or two of wood on previous cooks as well, but you may be on the right track. Here's my thinking...
This is the first time I've cooked such a small amount of food in the PBC. For example this weekend I cooked eight racks of babybacks (about 24 pounds worth), and the internal temp was relatively low, around 230 on average (they turned out awesome, by the way)...
With the tenderloin, two things were happening. One, since this cut is so lean, there were not a lot of drippings to cool the coals, so the wood chunks pretty much just caught fire and burned. Second, the cooker was very uncrowded with only a couple of pounds of meat hanging.
So, my unscientific hunch is that hanging more food lowers the temp a bit in the cooker.