Ut-oh!!! My experience is that whenever a kitty pees somewhere once, he will go back there again. Probably won't be your neck, but possibly the bed or your pillow....anything with the urine smell in it! My kittens were caught peeing in the corner under my computer desk as infants .... even now, they will try and sneak under there and I have to grab them and show them to the box. It's a convenience thing most of the time!
This probably sounds crazy .... and doesn't even make real sense to me .... ....... but I swear I don't ever smell when a cat has just peed on something (that is, AFTER it's cleaned) ..... but if a cat actually SPRAYS (on purpose, as in a male marking territory) THAT is nearly impossible to get rid of!!! I thought both were urine, so why would one smell worse than the other?

Oh well, try not to panic ... just buy a good enzymatic cleaner and try to keep that spot covered well so he doesn't smell it too easily again!