I think it shows that they are comfortable. I know when they are outside, mine will chew away, but will stop as soon as they hear an unfamiliar sound. Once they are no longer on 'high alert' they will resume chewing. I think they are just demonstrating that they find your pats very relaxing and when you stop, they are anticipating you starting up again!Thanks for the responses. Sometimes when I stroke them they will time their munching with the movement (munching when I'm stroking them and pausing when I move my hand). So maybe it has an additional purpose as well as eating?