Brown spotting

Hi everyone! I just got my BFP this morning by chance. I thought AF was starting Saturday because I had brown spotting and light cramping. I wasn't due to start until today. I had it for a few days but last night it tapered off so this morning I decided to take another test and whaddya know it was positive! Me and my hubby are ecstatic but now the brown spotting picked up again. Sorry tmi but it's more like tissue, not really blood. Is that normal? I've read a bunch of stuff online saying it's ok as long as it isn't red but after suffering a miscarriage in April I'm super paranoid now. Has anyone else experience brown spotting during early pregnancy? According to the date of my last period I am 4 weeks 4 days. Could it could be leftover from implantation?