I used to regret decisions in my life quite a lot. Changed this mindset and now I think regrets are for fools. Only a fool trips on what's behind him.
Quite smart motto however it is better to have regrets about something you did than regret that you didn't act. Forgetting about past failures also won't bring you any profits. I would say, that it is always good to understand your own choices.
Thanks to the understanding of a mistake one may take a lesson for the future. There's nothing wrong about own actions examination.
Sure that overreaction, anguish, starkness for yourself won't do any good but a short moment of retrospection, musing over past experience may. Especially when one has someone who could help, even if only by listening.
Sometimes I wonder if I could have corrected those mistakes if I had seek counsel from others.
Maybe it's more like remorse? I would say its a good sign, symptom of age, adulthood?
Like I said, those little moments of ponder over your life don't have to lead to your bad frame of mind.
Try to take out as much experience as possible from it, maybe some sort of revelation awaits you? An idea for awesome future.