I think that some Boxers DO grow a 'winter coat'. I volunteer for a Rescue group and just this past month we rescued a dog that had been outside since January 17 - he had a longer coat that Asia and it was because he had been outside for so long, he had grown his 'winter coat'. It wasn't really noticable unless you ran your hands through it or whenever you got up close.
Maybe there is a chance that the woman you spoke with kept her dog outside and he had grown his winter coat?
I could be 120% wrong, I'm just speaking from my personal experience!