Grade Boundaries Query

I'm a year 10 student taking higher separates science (edexcel). I have just recieved back my physics mock (we did a combined paper 1 as we hadn't finished all separate content when we did mocks). I got 54/60 which I was really pleased with, but then I was told that you needed 56/60 for a grade 9. To me this does not seem at all in keeping with the usual grade boundaries for this paper. They are usually around 45 for a 9. I wondered if they raised the boundaries as we are a separates class doing a combined paper, or if the teacher simply got confused. Does this grade boundary seem sensible, and what should I do if I want to try to ask a teacher about it? Thanks!