Yes, that’s one of the things I learned on the SDMB: A “kiss” is a search for the remnants of a kill.
Kinda related, a trainer we recently worked with recommends that you spit in your dog’s food. The dominant members of the pack eat first…
Where-as the cat says: “Oh goodie, my slave has returned for my amusement.”
Well, back in the mists of time it probably comes from that and from food-begging, but in modern adult wolves (and dogs) it’s now also a codified social behavior mainly indicating submission and also used in greeting contexts. Not that your dog isn’t also interested in what you’ve been eating behind his back…
JRB
The first thing my dog does is sniff me to see if I’ve been petting other dogs behind his back. He’s never trusted me since I took a neighbours Rotty for a walk. 
If the OP isn’t going to bother to go back to the threads he starts, I can’t be bothered to keep them open.