Mother seems more agitated. Is this normal?

My mother who is usually the sweetest person I know has had bouts of anger lately. Is this normal? She was upset about the trash the other day and was yelling and then yesterday was angry about the tv and takes it out on me her caregiver. She also stated that things that have Been here since I have moved in are now changed and she doesn't know why. I.e.: there are a lot of cords for the tv, vcr, satellite dish and tv's should nay have ONE cord. Is this normal, will it get worse. One minute angry and next doesn't remember and back to sweet self.