Why does my pet do this? Is it normal?

I have a cat that is a female and 2 years old; her name is Minnie. Minnie is acting very strange. Everytime she sees a blanket she gets on top of it and starts sorta petting the blanket while purring at the same time. I have never seen a cat do something like this before, and I'm getting a little bit worried. If you have a small clue of what's happening to her, plz tell me. Thx for reading!