I think that Apple uses an algorithm for the fans that monitors the rate at which the temp increases, the length of time it remains at the temp and the temp itself. If the run-up to 105 was rapid and took a minute in your case, it's likely that the fans would have kicked in after a little more time. If the run-up and been more gradual, the fans would have kicked in sooner. I've seen this same behavior. I don't like Apple's apparent focus on quiet fans over temp control, but that seems to be the way it is.
Until people start roaming in with melted logic boards as a result of this, I wouldn't label it as a big problem. These are too new to make any claims about a possible sacrifice in longevity due to Apple's focus on quiet fans over cooler-running laptops.