...having read a lot of posts, and just searched the site for 'leaky windshield washer' and the like, I can say fluid coming out of the nozzles when the car sits isn't a common issue. Does it only happen if the washer was used recently? Can you actually see (a lot) of fluid coming out, or just a bit of adjacent leftover drops/oxidation? Does it come out of one or both nozzles? Do the (one or both) nozzles seem to work the same/properly when the washer is activated?
I can imagine if a nozzle was slightly clogged there could be some residual pressure, but I'd expect that would only drip a little bit of fluid after the fact and it quickly stop. If you're saying the car is actually sitting dry and the washers weren't recently activated...and then all of a sudden a lot of fluid comes out (and the pump isn't on...)? That would be a headscratcher.