Strange behaviour indeed!! Maybe you touched something that smells nice to Scout, and then typed on your laptop and the smell is still on the keys....?

Piglet chews the newspaper but only when I'm reading it, just to get my attention.
Boyfriend's cat Wissel licks anything that's made of plastic, but I once read that that's typical behaviour for a cat who is bored and doesn't have enough room to get around and play (which is true because she lives in a very small one-room appartment , I think it's a bit cruel, and spend lots of time with her)

It could be Scout's very special personal quirky behaviour to lick the keyboard, every cat does weird things sometimes, which makes them even more unique.