I ate Brie that had been at room temperature for 48 hours. Should I be worried?
Brie should only be eaten at room temperature... and stored at it too if you want it to ripen - same goes for camembert.
Rule of thumb: For every one hour at room temperature, subtract one day from the use by date.
That depends on the temperature of your room. Lets not forget that not so long ago people didn't have fridges, and all food was stored in larders - people survived.