I am not a resident but have spoken with numerous residents at my home program and at others about this issue. The expectations are fairly low for fresh R1s and they often get simpler studies (e.g. MSK plain films, chest x-rays, etc) on their initial rotations in order to get their bearings. They gradually move to more advanced studies and cross sectional imaging with further experience. I don't think you have anything to worry about, especially since you've shown the aptitude to learn the anatomy when needed and in a more structured setting.