Maybe a dumb question?

About a week after my boyfriend and I let a hot and heavy moment lead to unprotected sex, I spotted for like a day and a half. I thought maybe my period was coming early but it only lasted that short amount of time. I know implantation bleeding is a thing, but can that happen that soon after sex? The health class I took in high school is the only sex Ed I've had and it was pathetic, so I'm sadly under-informed about my own body. Could this have been implantation bleeding?