what is the deal??

So my periods are pretty regular. 28 day cycle. have been spot on for months. Well I'm 2 days late. 4 days ago my husband and i had sex and i bled for a day and a half and spotted for a day. Now nothing. I thought maybe sex triggered it to start early but now im confused...? We use condoms and deff do not want a #3. Im not stressed at all. What could be the issue??