Help spotting 4dpo !!!!

So my husband and I are ttc. I made sure I kept track with my OPK and had intercourse when we were supposed to have. On day 4 after ovulation i went to the bathroom and after I wiped myself I say some blood on the toilet paper. It was kinda dark red maybe brownish. This happened only that 1 time and haven't had any other symptoms or signs. Si de e note, I never spotted in between my period. Could this be implementation bleeding? Has anyone ever experienced this.

Thanks !!!!