Ok...seems like now that it's cold out, I like to put the recirc button on when driving in traffic, due to the exhaust fumes being pumped in to my vehicle. With the Acadia, using the A/C this summer, I had the recirc on all the time - no smell. Now with the heater, I put the recirc on and it smells musty or something. Anyone else notice a weird smell with the recirc on and heater? It does not smell with the recirc off. Nothing has crawled up and died in my car over the last few months. ???