I An 54 Years Old And Have Not Had A

I an 54 years old and have not had a period for over 1 1/2 years due to menopause. 4 days ago my breasts became tender, 2 days ago I experienced cramping as if i were going to start a period and yesterday I began bleeding just like a regular period. I have scheduled an appointment with my GYN but wanted to know if it's common to have a period or hormone fluctuation after not having one for that long. I know the concerns about cancer but hope it could be some other cause.