Definitely understand the issues presented in high-temperature and high-altitude situations. But this was a 10 PM departure in January from DCA. So sea level and about 40 degrees F. It was a 400 mile flight, dead straight west, so I'm not sure how fuel loads could have been an issue.

I think in the instance I described it either had to be actual cargo (even if RJs traditionally don't carry it, I'm sure for enough importance/money it can happen), or something like a bunch of EXPs checking suitcases full of bricks.