What Causes Vaginal Bleeding After Having Sexual Intercourse?

hi. i am 28 years old. i have 5 kids. my last two pregnancies were c-sections. i had a set of twins and then i had a boy after the twins. i got my tubal after having my last child. which has been 4 years as of may. the other day i bleed a little bit after having sex. i thought it was odd. i dont recall doing that at all any other time. is it possible that i could be pregnant? i only spotted a little bit for a couple of hours afterward, and didnt do it again.my first two kids were natural deliveries.