Reallly light pink/brown discharge at 4 weeks

So I’m about 4 weeks and 2 days pregnant. I went to the bathroom and wiped to find really light brownish pink discharge. It was only there for a couple of minutes and I haven’t had it again tonight. I’m having normal pregnancy cramps nothing serious. Do you think it was implantation bleeding or Maybe from sex the night before?

I’ve never had bleeding with my first two pregnancies and my last pregnancy resulted in a miscarriage at 17 weeks.