This not a metaphor.
In my book, once the spoon has been in the mouth it stays out of the of the shared pot. To be clear, I don't think the plague is going to be spead (although he still does it while bemoaning a vicious cold) but I prefer to choose who I share slevers with.
I'm not going to mention it to him, I have learned to get to the unopened pot first and memorise the ones to avoid but AIBU? Should I shake aside my gag reflex and welcome this as a deeper level of intimacy that could strength our familial bond?