When I worked in corpo, there was a deaf and mute person in the mailroom. She became my friend because I used to hangout there when the office is not quiet enough for my peace.
We would write each other notes to communicate but one day I thought I should learn the ASL fingerspelling. I learned it and didn't tell her so one day I went to say hello and blasted her with my finger moves.
It made her very happy. Genuinely happy.
ASL is like riding a bike. Once you learn it, you don't forget it. Might be a little rusty at first but you don't forget it.
P.S. She could also lip read very well so she always knew the gossip.