UML isn't really like hiding a bike: after some time without practicing, you do forget how to do it.

I've just googled "uml class diagram reference" and got Allen Holub's UML Quick Reference as the first hit.

I mean, you'll never forget the logic and semantics of a UML class diagram, but its syntax. If there are advantages in using UML, the most important of them is that people can undertand what you mean with a design. Buy, anyway, that would be that good without using the right symbols in the right places, huh?

Did you remember the difference between the white and the black-filled diamond arrow ends in class diagrams?

Oh, yes: drawing diagrams with a bad mouse sucks too much.