Are u sure?

Normally people do some nice things to others, the others accept it and say thanks.In this country, I found people like to say: are u sure.Today I give seat to a pregnant lady who came in the train and standed by me. She asked me: are you sure? I said sure.I also remember my first day in my new job. When my manager insisted on pay for the lunch as a company lunch, the other colleague said: are you sure?People want do some nice thing, he or she must already make the decision. No need with that doubt attitude any more.