I might tend to agree with the idea that some surgical chemicals, even anesthetics, can be stored within the body, and subsequently released.
My past experience tells me that at certain times, the body metabolically uses the reserves within the cells as energy, and that's when the "smell" can be released. If this is the case, you will be picking up that odor untill the substances are used up.
I have seen this in humans, but it is entirely possible in any mammal, I would guess . Still, to err on the safe side, has infection been ruled out? (shouldn't have that smell though..) Has your surgeon been been asked?
Either way, best to you, and let us know, I'm curious now..