I am interested to find out the answer to this. I received a high pass at one of my rotations. Not sure what happened, but felt I worked very hard and was always very prepared.

I received a HP on one of my aways, still ended up matching. I am not sure if it was actually on my transcript but I was never asked specifically about my grades and I was told on multiple interviews that my letters were good. At some places attendings are supposed to give out a certain amount of H, HP, P, etc I think that was the case at my away and that is why even though I got that grade I was still given a good letter. Hopefully that is the case for you all as well and it doesn't end up affecting your application negatively.

Some schools only have pass or fail for seniors anyway. I would just move on and rock the rest of your rotations.

Where was this? Total dick move, in my opinion. Unless you did a really bad job, a 'pass' rather than 'honors' could actually hurt you. I'd 100% reach out to the PD and find out what happened.