Bleeding while sex

Had sex about a week after my period ended and there was a lot of blood. I didn’t feel anything but it kind of freaked him out. I only had sex once before but the bleeding was very minor and I anticipated it, I assume cuz it was the first time. Is it possible that sex dislodged the cervix lining that didn’t completely shed? and how common is it. I don’t want him to worry about it much.

I should mention we did it twice and the blood was the first round. 10 mins after we did it much rougher and there wasn’t any so I was thinking it is probably the remaining lining that wasn’t shed. Just wondering if anyone else has experienced the same