Small drop of blood- Normal or not?

Kara

I'm 17w5d and not sure whether I should be concerned or not. I just peed and when I wiped, I saw the smallest spot of red/pink blood on the toilet paper. It was just the one small drop and that was it. Should I call my obgyn or only call if I see more blood later? I haven't had sex in 2 days, but I did workout a couple hours ago.