What Causes Vaginal Spotting While Taking Utovlan Tablets?

Hi, I have PCO and have been constantly bleeding for seven months. I have been prescribed utovlan almost two months ago. I have to take three pills a day for three months with one week off to allow bleeding. However, I just started spotting two days ago and slightly bleeding now. Is this ok? As I was under the impression that I will not bleed for the next three months. Thank you.