It seems your dogs have given you the answer that the odor did likely drop and pool under the chair. 🙂
Yes, absolutely, fabrics will hold odor much more than harder surfaces, tho’ plastics tend to grab odor as well. If you’ve ever put a hide under a rug, until the odor has had time to expand it can be quite challenging for the dog to find. And after the odor has expanded it can become a challenge of finding source.
Joyride K9 Dog Training