Leaking fluid?

Im just about 33 weeks, and just about an hour ago i felt a small gush and went to the bathroom. Up until today i always had normal pregnancy discharge, which i feel like i can recognize now. However this time there was discharge plus a clear watery circle sized wetness about 8 cm wide and 8 cm high on my panties. It hasnt happened again since but i am wondering if it is worth calling l&d;? I have an ultrasound appointment on january 2nd, can it wait another day or should i call just in case?

Any input would be nice. Thank you!