When we've had that happen to us, we vent then hold in the same foil/liquid we used to wrap (maybe baste with the liquid before closing back up), and then wrap a towel around them - to hold in some heat but not continue cooking them. This was ideal when we slightly overcooked our ribs and had to get them to firm back up a bit.
The 5th Artery BBQ
KCBS / NEBS / CBJ
MAK 2 Star General / Yoder YS640
2 - WSM's 22 1/2 / 3 - Weber kettle's