There's a definite difference between "pick up the syntax" of a language that doesn't have (m)any new concepts to wrap your head around versus learning new concepts embedded in a language.
Javascript has closures and functions-as-first-class-objects. Haskell has monads and all that jazz (I haven't used it yet). I'm guessing you didn't take months to learn the syntax of javascript, but to think in javascript.
It's similar to the difference between being functional in a natural language versus being fluent in said language.
necro said pick up the language and syntax -- I took "the language" part to mean the concepts of the language outside of the explicitly mentioned syntax. With that said, I felt addressing his comment was necessary since writing idiomatic code is not something that should be expected from a weeks worth of experience in a language.
In essence, I'm agreeing with everything you said, just wanted to clarify the reason for my post.
"Pick up the syntax in a week" is a huge black flag in my book because it indicates the developer doesn't really understand why his paycheck shows up every 2 weeks. Expertise is learning an environment's vernacular, gotchas, and detailed ins-and-outs of the frameworks/apis. It has nothing to do with passing a Programming Language 101 class.
So am I not a real developer because it took me longer than a week to get a hang of Haskell? Hell, it even took me many months before I understood JavaScript well enough to find the right mix of patterns and practices to write solid code in it.