rick79, morning.... There is a rule about "whole intact muscle" when it come to cooking.... The outside of the meat needs to come to 150 or so for an hour or so to kill the surface bacteria.... Then it can be probed with a therm and no bacteria will be "pushed" into the meat..... Then the cooking time is "somewhat" irrelevant and the time temp calculations don't directly apply.....
As long as the smoker temp cooked the outside of the meat and it was not probed when cold, you are good to go... That being said, the IT of the roast at 140 was probably there for a long time and the surface temp quite a bit higher, and I would eat it, no problem.... There is also a "holding" time temp rule Chef JimmyJ can explain... Holding the meat at a given temp, say 140 for 3 hours, (or something like that, don't quote me) will kill all bacteria and make meat safe to eat...
Sounds like the temp just dropped in the smoker..... I would bring it back to 225 and finish it off.... 205 or so for pulling....
Dave