Cornish Yarg?
Not normally. There is actually very little of the acid left in the nettles if any after the nettles have been blanched. Most 'reactions' if there are going to be any are usually in people's heads because of the inbuilt responses we learnt as a child. Avoiding being stung. When I first started cooking nettles we took a while to get used to their 'furry' nature even after the sting which is one of the reasons that only the top 2 bright green nettles leaf pairs should be harvested and in spring. As the leaves darken and grow, they get more of the acid in them that causes the skin irritation (the acid is in the sting which is basically the furry bit of the leaf and stem). No stems should ever be eaten. They are best left to grow as high and tall as possible and be harvested in Autumn or Winter for weaving with or making yarn (the long the threads inside the tough outer are the easier it is to spin them into twine - I've done it several times over the years, but it is very labour intensive). IMO it is better to harvest and eat the fresh leaves in spring. I have a wonderful nettle gnocchi and nettle bread recipe.
So back to your question - any reaction would be immediate and life threatening - and I do mean immediate as in a pretty much instant response and a 999 job. (Though I do know of people who have mastered the art of eating nettle leaves but they are selecting very specific leaves before much to any of the acid is in them, and roll them in a specific manner and so on).
As for the leaf coating on Cornish Yarg (the only one I know of that uses nettles in a cheese), I would be stunned if there were a reaction other than it being a first time I've knowingly eaten nettles and its new to me and I only know them as stinging... (sorry)