This may sound a bit odd, but I left my cat at a friends place (who has 2 cats) for about a week, while visiting her very often (almost every day). She came home and all of a sudden picked up this licking habit. When I am about to wake up she'll come lay on my chest (which I've trained her to...
My kitten does that all the time. When I rip off a sheet to change it and put it in the garbage, she'll go in it just so she can lick it. Maybe it's the roughness against the tongue? Who knows.
