Actually, the problem was that the Ryanair check-in girl didn't speak German so didn't understand what the notation "Erwerbstätigkeit nicht gestattetet" on my visa meant, so she called the Lithuanian immigration folks who didn't know it either and had to refer to someone else up the chain. Not that it was any of her business checking the visa in the first place for an intra-Schengen flight, but to be fair there is nothing else to do at Kaunas Airport so this at least gave us a little bit of excitement.