Front Differential Problem
 

My 2008 H3 is currently at the shop after smelling "hot" near the front tires off and on for the last two weeks. The mechanic said that my front differential was leaking and it appeared to be separating from the axle. I am by no means a mechanic, so I am just wondering- How does this happen? I don't offroad, or anything like that. I simply drive to and from work. I asked the shop the same question and they said they wouldn't know until they dug into it some more and they have never seen a situation like this. Luckily, I am under warranty, but this makes me wonder about the mechanical future of my H3, as I only have 43,000 miles on it. Is this a sign of things to come?