My boss found out I'm not as smart as he thought.
An example from my experience:
I'm a junior programmer, and I work in a team of two, my boss (senior programmer) and myself.
I was tasked with developing an internal web-application for the company we work at. I wrote the back-end to the front-end (the database design was in already place and the server technology had been chosen). He would periodically check on my progress by observing the web-application in action and was happy with out it was coming along. When I finished the web-app he was pleased with how well the end-product turned out.
So given this example my question is:
If your a senior programmer and have lost confidence in the ability of your junior programmer, what would you like to see from your junior to gain the confidence back?
EDIT: Thank you everyone for the great answers and supportive feedback!