light spotting?

Im 17 weeks and last night noticed some very light pink tinge on the tp after using the bathroom. It stopped almost immediately, but of course I was freaked out since I haven't had spotting before.  Called my midwives this morning who told me not to panic and to call back tomorrow to schedule an ultrasound at a nearby hospital. I'm just wondering if other ladies experienced this? I'm having maybe a tiny bit of cramping but nothing major! help? advice?