Spotting and the Birth Control Pill?

I've been taking Yasmin for about 3 years. My gyn told me I could skip the placebo pills and continue with the active pills in order to avoid my period some months. I've done this two months in a row (my last period was in mid-november). Well, now I've had brown discharge since before Christmas. I called my gyn, and the nurse said it's just my body adjusting to the pills. I had a gyn appointment right before this started and the pap smear was clean. Should I be worried?