"What--oh god, no, even I know that's terrible relationship etiquette for everyone except penguins." He has another bite. It might be near impossible for him to keep track of things in the normal, regimented ways other people do, but he knows his last full meal was a couple of days ago and it's a good idea to refuel more often now that he knows he'll be devoting some energy to... emotional stuff. (Okay, and sex.)

Plus, rather than being the crack in a lens, Molly's presence just sort of tilts that lens a bit so it's turned on different things. Not only can he taste all the ingredients, but the tastes register as something he likes. Something with value.