The Virb does get a little too "hot" when the battery is being charged or when it is recording for awhile. This is because the battery is charged in a water-tight (IPX7) battery compartment. I would hazard a guess that the product designer did anticipate the heat that is going to be produced and catered for a ventilation hole on the battery cover to aid the dissipation of the heat - this hole has a blob of glue on the reverse of the cover, supposedly to ensure that water does not get in.
I won't know if the amount of heat generated is enough to cause condensation within the unit in my hot and very humid country, would anybody think it's a better idea to remove the battery cover when the unit is being charged?
