Sounds normal, my doc told me in my first pregnancy not to worry about being too rough during sex,as long as you are not feeling pain or bleeding everything should be fine. Just do what you feel is comfortable, but it is a good thing that you noticed because it is better to be safe than sorry. Good luck with the rest of your pregnancy and God bless you and your family.
For anyone who may read and is interested: turns out sex can knock lose a bit of the mucus plug which can grow back. Unless accompanied by bleeding/cramps/contractions doc said not to worry