Brompton brake cable wear issue

Although my Brompton is lighter than most, it's still too heavy to carry through the length of my office building or the Metro station. As such, I usually roll it around in the folded "shopping cart" position, with my bag clipped in place. This way, the bike rolls around on its two EZ wheels and the wheel on the fender.

As I did this I noticed that, with the weight of my bag, my bike would sometimes lean in such a way that the bag was rolling on the front wheel in fold position, an EZ wheel, and the fender wheel. The bike actually rolls pretty well this way, allowing for the weight to shift back and forth, so I thought this may have been intentional on Brompton's part.

I had been doing this for about two months when D noticed that one section of brake cable housing was worn away. At first we couldn't figure out what happened because the damage was at the front by the fender, on the side facing out. So we folded the bike and soon realized that the cable was rubbing against the front wheel, and the housing must have worn down as I was rolling my bike in shopping cart position. Lucky for me I was due to take my Brompton in for tune-up, so I was able to get the housing replaced right away. 

I guess a folded Brompton isn't meant to roll on the front wheel after all...