I'm NOT an expert at this but "go until tender and temp is just a guideline" always rings true.
One variable that impacts tenderness is how hot the pit has been cooking at. The hotter the oven, the higher the meat will have to go before it gets tender.
325 isn't "low and slow." If you had been going closer to 225-250 it would have taken longer to reach "all done" but you could have stopped everything at a lower temp than 210 in the meat.
Sounds like you'll be OK so long as you let it ride, but dob't dry it out too much.