Bleeding during ovulation and sex

Ok so my period ended a week ago and I am currently ovulating and during sex my hubby noticed I was bleeding. I went to the bathroom and sure enough I was bleeding light red. After a few wipes it was very faint but I Ended up put a pantie liner on just in case. This has never happened and I wonder what does this mean and why has this happened? Anyone experienced this or know why it has happened?