Mine lick their lips after they eat, too. I'm with Jessica - I think they are trying to get all the microscopic bits off their mouths.
And turkeylegs, my little girl - Andy - usually lets out a pretty big "brrrrrp", too. Those girls...he he. No seriously, Rhys is so much more delicate about his bodily noises, his drinking, etc. But not Andy. Are Corgi girls less, um, restrained?