If you're not menopausal and have regular periods, it is probably normal. If your period
seems to go on spotting for days longer than usual
, it could be a polyp in the uterus (very rarely cancerous), which also might be found with the endometrial biopsy. It all could be hormonal change, as well. If you're under 40, the likelihood of it being cancer is quite slim. I'd still go ahead with the biopsy, anyway.