MacBook Air not letting me in.

I had a scare this morning. I powered up my MacBook Air and was presented with an Apple message saying that I had forgotten my password, which I hadn’t, I hadn’t even typed it in. I was given three options. I chose the one that said I couldn’t use my keyboard (which was sort of true). That after switching off and starting up my Air twice to see if it was just a burp from the computer - no such luck.

Long story short, I got in but only after having to decrypt the disk! I can’t quite remember how that happened, but the options that I was presented with led me to that path. I’ll encrypt as soon as it is done, unless it is possible to safely stop the process - does anyone know?

All this two days after I’ve upgraded to Catalina.