Work Place Social Problem?

Recently, For the past six months. I have been having lunch with one of the girls in my office. Continuously,she tells how much she likes this certain protein bar. So,I happened to buy her three little bars and put them on her computer desk this morning. When she came into work, all you could hear saying is OMG. She came over to my desk put the bars on my desk. I told her I bought them for you.{ Never said, Thank You.It nice you thought of me,etc.} { I didn't want to start anything at work} As I walked from my desk. I could hear talking and shouting ,Never buy me anything again! I was shocked,hurt and went over and composed myself. I know there are people who don't want gifts. But I have people approach me in a different manners to relay that message. Help me. I don't know if I want to have lunch with her again. Please don't say, go talk to her and everything will be fine. I see her as being very hot headed and doesn't accept criticism.