I (42M) have a friend (25F) in work who occasionally buys me chocolate bars that I like and leaves them on my desk. She is a very kind and generous person, our relationship is platonic and we initially bonded over shared musical interests. We get on very well and occasionally chat outside of work too. I appreciate her generosity, but never know what to buy her as she has special dietary requirements.

She gave me two bars of chocolate recently and I thanked her and said something like I never know what to buy her. She sort of just looked at me but didn't say much. I don't know if she was annoyed at me for not knowing what she likes or if she was annoyed at me for feeling I need to repay her generosity. She didn't get annoyed with me and things were fine between us afterwards, but maybe I should have just kept my mouth shut.