I have no problem with you reporting any issue you have experienced. My comment was more directed at the "known issue" since two reports don't to me indicate a model wide issue. If it really was a model defect then I would expect Piaggio to do a recall and replacement like they did with the fuel pump issue.
FWIW, we have 2 BV 500. Both had an initial problem taken care of under warrant. On my BV it was the speedometer. It went from being within the normal bike error to being as much as 20-30mph off and the low fuel light quit working. Piaggio replaced the entire speedometer which took about 3 weeks to come in (August when the dealer diagnosed the problem.) So if the problem with the mirror stems is a Piaggio issue, even if it is just a single batch (VIN number indicates probably same shipment of lights for example) it is something for Piaggo to address.
My husband's BV 500 had the exhaust fail on a trip which not only made it sound more like a Harley it also reduced the mileage to that of a Harley as well (resulted in running out of gas 2 miles short of the next gas station in West Texas, grrr). There was significant back pressure in the fuel tank as well. Exhaust was replaced under warranty and the back pressure resolved by the dealer removing the evap canister.
I've never found another BV 500 owner with the exhaust issue but there are complaints about the speedo & fuel lights. Not enough to call it a systematic issue with the scoot. My GTS on the other hand has never had any sort of issue nor has the Sports City or Scarabeo. I did have an issue with my 2007 Scarabeo but I'm pretty sure it was caused by the previous owner's modifications.