Thanks for posting your query at DoctorSpring.com
3 years straight with no periods technically falls under the definition of menopause.
So this bleeding counts as post menopausal bleeding, which is definitely not normal.
It warrants investigation.
It could happen due to mild hormonal imbalance , leading to growth of the lining of the uterus.
Again, it can happen due to local deficiency of hormones, making the vaginal mucosa brittle and easily prone to bleeding and spotting.
You need to consult a gynecologist, have an internal exam, a Pap smear , a pelvic transvaginal ultrasound scan and hormonal levels to confirm menopause - FSH, LH, Serum estradiol and TSH.
ALso, please have an endometrial biopsy if the ultrasound scan suggests that the uterine lining is thickened beyond normal.
All the best
Please feel free to discuss further.