Is this common?

I have been taking Yaz birth control for three months now, and I just ended the third month, but during the four days of taking the "inactive" pills, I did not get my period like I was suppose to. It did say in the booklet that sometimes you miss one and to go on taking the pills and just let your doctor know.  I’m going to call my doctors office tomorrow, I just didn’t know if anyone else knows if this is a normal thing or not.   I have never missed a pill, and the few times I did have sex, the guy pulled out anyway, so it seems to me the chance of me being pregnant is very unlikely, although I know still possible.  Anyone have any input…?