What causes repetitive actions?

This site has so much good information. I am thankful that I can come here and look for information. This is my question. I've noticed that my mother, who is 92 and doing well, does some thing repetitively. I noticed it about 2 years ago and did not think much of it until my spouse and I were discussing the subject. We really want an understanding of why for example, she takes clothes out of the suitcase and puts them back and repeats this. She folds bags, unfolds them and refolds them. We just want to know what is going on in her mind when she does this and if there is anything that we need to do or look out for. She does have some forgetful issues, but not as serious as some that I have read about or have personal knowledge of. She is very independent, lives alone, still drives, goes to exercise. We are not trying to take away her independence, but just want to understand.