What Causes Heavy Bleeding During Menstruation?

I had the IUD Paraguard inserted Monday, 1/10/11. I was close to starting my period (1 day away) and usually do have a slightly heavy flow. However, I am bleeding more heavily and it is more liquid and 'bloodlike' than what I am used to. My gynecologist said to expect a little more bleeding, but how much is too much? Is this normal or should I be contacting my gynecologist?