There's something peculiar about playing a big beautiful chunk of highly expressive music like the Brahms concerto. When you do it, you have to do a lot of self-inspection. You have to get in contact with your feelings. You have to analyze yourself and the reasons behind everything you do. You have to suddenly become sensitive and in touch with your emotions and when you play you wear your heart on your sleeve.
I am happy being a big insensitive caveman 99% of the time. Every time something like this comes up, I become a big blubbering mess, blathering on about how things make me feel. I start using words that never come up in my vocabulary; words like "self-esteem", "support", "insecure".
Normally you can count on what I am going to be like at any time of the day. Quiet, impatient, indifferent to most of the world around me, always with a very direct and a bit of a rough way of saying things. People tend to be scared, or impressed by me. They think I am an ogre; maybe they are right. All of a sudden, I am extremely worried about what other people think of how I play. I question the motives behind every compliment, or lack of. I become super-sensitive to all criticism.
Playing these monumental works of art does that to a person. I just want it to pass so I can get back to being myself again.