It is probably just me, but I have very mixed feelings about it. I like the idea but either it is too short or too long. Like I get the joke, but because set up for it is so long and then once she sniffs and we know where it will go, we have entire conversation before the "punch line" lands and then they still talk some more, it feels a bit dragged on and feels like it would work better as quick, few panels joke. The way it is right now it feels like a set up to serious bdsm story which then suddenly turns into more light hearted one and either forsake the bdsm theme entirely or continue it with more playful tone. Basically it feels more like first few pages of doujin with rest of them missing, which puts bummer on reader (me), because I want it to continue. Take it as you will.
I very much appreciate your detailed thoughts! Thorough feedback is a godsend.
My intent was mainly to show the two characters in a positive light, and also to show that a BDSM relationship can be warm and loving. The joke is a means to that end, rather than being an end unto itself.
I dunno if that will enhance your enjoyment or not, but there it is.