Ambient temps would be a factor...
Evaporation has a cooling effect -- it absorbs heat when the phase changes liquid->gas. If evaporation was a strong enough effect the first few days, it could be the primary reason why the temps went up slightly -- assuming ambient temps and house furnace didn't sway a bit, too. Probably more than 1 thing at work here.
This is how 'evaporative coolers' work and also why tehy don't work well in higher humidity due to a reduced evaporation rate in that context.
Adjust whatever you need to get the climate variables you want... as long as the fan isn't directly pointed at the buds, sure if it helps.