Really, it is in the rental agency's best interest for someone to bring up the odor issue ASAP. For a variety of reasons, the staff at the rental agency either ignores the odor issues or does not notice them. But even after the car is parked at the garage a while with windows up, the issue can come back when you go to your assigned vehicle. The longer an odor issue goes on, the harder it is for them to fix.

Definitely not something that it is reasonable to expect compensation for. Especially since if you wait until return to bring it up, there is no real proof that you were not the one who caused the odor issue in the first place.