I can't resist stroking Julie from her head, down her back and all the way down her tail when she is in the 'meatloaf' position. She also does that sound...sort of a flutter sound. Her body will rise up in a wave as my hand slides down her back as well.
She makes the same sound whenever I feed her... she will hold her nose up to me for a smooch before she eats, most of the time... (sometimes the food is just too yummy for kisses). I figure its her way of saying 'thanks Mom!'