Is THAT what those noises are?! And here I was thinking that it was my fault she made those noises, because her brother and sister are cats! I always called it her trying to purr, but it's really more of a moan/groan under her breath.
When she first did it as a puppy, I thought we were hurting her, but she does it when we're not even touching her too. Almost as if she's sighing when she gets comfortable. Or sometimes, if we're in bed and DH and I are talking, she'll do it as if to say, "shut up and go to sleep already!"
The little brat!
I had no idea this is common among Yorkies! I learn something new everyday!