I think you were fair. jQuery selectors are pretty easy stuff, and you can pretty much guess at the jQuery interface and probably be right.

This is coming from a python guy who does very little javascript.

If he did get some of the methods wrong you could always ask the candidate what he thought the method did. If he knew there is a method to accomplish a specific task and he just got the name of it wrong that I'd say he is good to go. He can always google that kind of thing on the job.