Absolutely nothing wrong with using an herb that has been on this earth for longer than mankind
Psychoactives such as marijuana can be great, they have the potential to alter the lens of your perception and give you the temporary gift of perspectives that you could have never seen before with the ego and thought patterns blocking the view; they are beneficial when used as a learning experience, and can be of great help spiritually and psychologically to get past barriers. These kind of experiences have definitely altered the course of my life in a positive direction.
Here is a suggestion to answer your question, realize that whatever the potential for confidence you unlocked when you smoked with your friends is always there. Integrate that experience into your whole being, for it will make you grow. Realize that nothing ever shifted but your point of view =)