One of the best activities after a concert is to talk about it over drinks. For musicians, talking about a concert that has just been performed boils down to a musical postmortem. What went well, what went horribly wrong, how it could (read: should) have been better, are all tossed about over beer or wine.
By the nature of their training, musicians are trained to be hyper-critical with their own performances. Whether it is solo, chamber music, or orchestral music, the inner critic never shuts off. And while this is a very good tool to keep skills sharply honed, it can be detrimental in certain situations.