This is no biggie, just something very surprising for me.
I've a very close friend that I'd known for 10+ years, we met through work several years ago. A few weeks ago I was helping her move/unpack to a lovely new house, and staying there for the weekend.
The house had a piano. I was amazed to discover that she is an incredible pianist. Really really amazing! She says she was somewhat of a prodigy when young, but lost interest and motivation in teen years, and is just re-connecting with it as a hobby.
Sadly, if I was that good at something I'd have let everyone know :(