After reading this thread it dawned on me that I've been topping the air in my front tire way too often. All my other bikes are tubles, the HD sits in Florida for eleven months and loses very little air. So I called the dealer, the service manager suggested that I tighten the valve, which I already did a week prior to my conversation with the sm. He also suggested I do the soapy water test, which I did, no bubbles presented themselves. Next call he suggested I pump up the tire to 40 psi and check in a week. The Bobber wasn't ridden that week and when checked the reading was 35 psi, the ambient temp was about 5 degrees colder. I called the sm and told him my findings, he said he'll check with Triumph to see if they would cover a tube change. Two hours later he called to say that Triumph will pay for the tube and labor. He also told me that he's seen this issue on other Bobbers. I think after two plus years of selling Bobbers the manufacturer must be aware of this problem.
I believe that whether one gets a good outcome depends greatly on the dealer, mine has always been very responsive, to me that is more important than getting the cheapest price when purchasing a bike or car.