Spotting before FET transfer - is this normal?

Has anyone experienced bleeding in a FET cycle before transfer? I went for my lining check yesterday and it was good and I’m scheduled to start pio shots today and applicators tomorrow. Today I noticed bleeding after sex (which I have experienced on occasion in the past) and I’m continuing to spot. I’m scheduled for a transfer on Friday and one more day of monitoring on Wednesday. I’m currently taking 3mg estradiol 2x/day plus doxycycline 2x/day.