6/10 무료 매일 텝스풀기 1번 듣기 지문중에 only를 어떻게 해석해야할지 모르겠어서요

 According to Christie Williams, even though she was aware of the backpack's contents, she felt that it was only proper to look for its owner.

only가 proper같은 형용사 앞에 왔을때 어떤 뉘앙스로 읽으면 되는지 잘 모르겠네요 ㅠㅠ