Is there a Riesling wine label with leprechaun?

No, but it might be a troll, gnome or other (Little people) type character from Germanic folklore. what were called Kobolds were said to haunt mines and disrupt tools of legitimate miners- they were alternately said to (beneficially) warn miners of impending hazards such as floods or cave-ins- or as bad guys to cause mining accidents- which there are many- there was talk like ( Don"t let the Kobolds get your mallet, or crowbar, they were blamed for stolen tools and implements, my guess even walking off with Hand trucks- used in German mines since almost Elizabethan days.