Going to give the short version of a bad situation that Harley has started.  Simply if they see a Harley with a trailer hitch they will photograph it, take the VIN and turn it in to the corporation which will flag your bike.  What that means is your warranty is voided and no matter what's wrong with the bike you will have to pay.
This has nothing to do with the perforamnce of your bike it comes down to the trailer hitch not being a genuine Harley part.  What next will they say oh you have another brand of handgrips or a Mustang seat.
Understandable sales are down due to the economy but is this the way to retain your customers?
The above happened to me.  When the dealer was putting on my trailer hitch, that I have had on Ultra's since 1993, the Harley area rep. happened to be there took the photo's and sent them in along with the VIN.  Had a problem with the bike and the dealer made repairs and sent the paperwork to Harley to get reimbursed and that's when the flag came up and they would not reimburse him.  My dealer has fought this and Harley's answer is if I take off the trailer hitch they'll remove the flag.
So be careful of the Harley trailer hitch police, they're out to screw you.
Butch  

Sorry that happened to you. It really doesn't make sense to me why they would do that. I really don't see how having a trailer hitch does anything to the bike that should void the warranty. What ended up happening?
Mike
www.myharleyauctions.com