Why does my gran keep her drinking mug raised in her hand for about 30 minutes or longer?

Hi
I've noticed my gran keeps her mug raised in her hand instead of putting it down between sips. Sometimes she doesn't sip at all. She can keep it raised for over 20 minutes.
When she goes to bed her leg is bent at the knee, heel on bed and knee up. Much later she straightens it out. She says she is not stiff but she seems to lock into these positions.
When I do exam where you move leg around and tell her not to make her leg floppy it is quite stiff? 
Anyone else experiences something similar?