I have not and I'm actually really bad at learning human languages, but know a dozen programming languages. You would think they would be similar, but for some reason it's really easy for me to program in any language and really hard for me to pick up a human language.
I provided it as a counter example to the learning how to bike myth.
Learning how to bike requires only a handful of skills, most of them are located in the motor control centers in your brain (mostly in the Cerebellum), which is known to retain skills much better then any other parts of your brain. Your programing skills are comprised of thousands of separate skills which are mostly located in your frontal-cortex (mostly in your frontal and temporal lobes), and learning a foreign language is basically that but more (like 10x more).
So while a foreign language is not the perfect analogy (nothing is), I think it is a reasonable analogy as a counter example to the bicycle myth.
Maybe something that keeps programming skills fresh is that after you learn to think like a programmer, you do that with problems away from the keyboard. Decomposition, logic... in the years I wasn't programming, I was still solving problems like a programmer. Getting back behind the keyboard just engaged the thought processes I was already keeping warm with practice.
