4w 2d/3d and spotting brown for 2.5 days. Could this be normal?

I am 4w 2 or 3d and got my BFP 5 days ago and it seems to be getting darker and darker. I have had dark brown spotting for the last 2.5 days, started around when I was due for AF.

A single panty liner is fine for the whole day and far from full. I notice it a bit when I wipe too, but it’s not a flow.

I have not had any pain and my HCGs 2 days ago were normal.

Has this happened to anyone else?