Blood trace in urinalysis?

So I had a routine appointment today and everything went well and looked normal. The thing is that when I got home I got an email with notes of my appointment,which I get every time, that said there was a trace of blood in my urine. Everything else was negative for UTI, glucose, etc. I don’t really feel worried since my doctor didn’t say anything about it, or get a call from the staff, but I was wondering if anyone else knew what this meant. If anything I’ll call my OB’s office tomorrow but I just want to know if anyone else has had this.