Has anyone else's loved one with dementia displayed this odd behavior?

I realize dementia can cause strange behavior. My husband, who has later stage Alzheimer's and is on hospice, has started to do the weirdest thing. He's gotten fixated on other things before, but now he's rubbing any type of material - for hours. For example, I'm caring for him at home and he's been restless at night recently and not sleeping well. He'll rub the quilt or the sheets on our king bed - or my pajamas - between his fingers for literally hours. If I try to pull the material away (like my pajamas so it doesn't keep me awake at night), he'll put the material in a death grip to hold on. He used to feel kleenex and toilet paper, and now he's doing it with other material. Has anyone else seen this - or have a clue as to what's going on?