Okay, so someone else to wade in with another point of view.......
Tyre sizes are recommended to tyre manufacturers based on information from the bike manufacturer but are not mandatory..... With regard to the oversized 190/50 instead of a 180/55, the everyday rider may notice that the bike might turn in a little slower but have a bigger contact area. I picked up a ZXR750 back in the day from Bristol and rode it back home to near Norwich which had a 190/50 fitted instead of a 170/60!!. The bike was absolutely fine and seeing as money was tight back then it got ridden for a good few thousand miles before changing it. I did notice the turn in speed was much quicker after fitting the correct size and the back end was a bit higher.
Also had experience the other way on my ZX7R, standard fitment 190/50 and i went to a 180/55 to speed up turn in (and also added 10mm of ride height
), again no drama's, no omg moments from the tyres, just grip.
Bottom line from my opinion is although the tyre is a little oversized, it isn't dangerous. As you have stated, the bike runs fine and feels great. When you start dragging the pegs on the road and feel the back end losing grip then get it changed. If the dealer is happy to change it under due diligance then happy days, if not don't be frightened to ride it and just enjoy it.