My kitten has a special fleece blanket that's been with her since she's days old. Normally, she loves to play-fight with her blanket. Recently, I noticed something else. She loves to suck the end of her blanket while kneading it at the same time. The look on her face is pure contentment, coupled with really loud purrs. Whenever she does this, she look as if she's under a spell, in a trance or somewhat.
I am not stopping her behavior since it seems to really calm her down and she'll fall asleep right after her elaborate ritual. A little curious to find out if any other kitten exhibit something similar.