Implantation bleeding vs procedure bleeding

Hey there! So I had my 6th IUI on Tuesday and yesterday morning I presented with some brown spotting. I got really excited because I immediately thought it was implantation bleeding, but I called the office anyway to ask if that could be it. They said it could be blood from the catheter causing some damage to the uterine wall during the procedure. I’ve never had either so it’s so hard to tell what this is! My 3rd cycle I got pregnant but lost it at 7 weeks and all I had was light cramps. It just seems weird that it would take four days for bloody show if it was the catheter. Anyone have this experience?