My boyfriend best friend

So me and my boyfriend went out to meet his friend ( btw he wanted me to come) we went to a car meet and I didn't bring my coat and it was freezing and my boyfriend said do I want his jacket but hes a small and I'm a large so I said no anyway his best friend ending up giving me his jacket ( hes a bigger size) and I did wear it the whole night my boyfriend isn't bothered by it but i just want to know if it was bad of me to do it or not... just a question.. his best friend is old school and never would flirt with one of his friends girlfriend just to put that in there hes a sweet guy