Crown seating acceptable but not "perfect" what can happen? Should I have it fixed?

I had a crown replaced on tooth number 13 earlier this week. A temp was placed. The temp broke 3 days later but the permanent was ready, he decided to place it today. He went to cement it and my gums were still sore from the work earlier in the week. I flinched and he said that it may not have seated right because I moved. They took an x ray the dentist said it was acceptable but not perfect. Said it was off by a milimeter. He felt it was 98% out of 100% they're insisting it should be fine