I think I can predict that he will think it's "normal." You may have to wait until it's happening in 60 degree weather to get any help from the dealership. What may it be? Look to see if a single blue charging light comes on above the dash overnight. That means, depending on the side, that either the battery warmer is running (improperly in this case) or the car is charging the 12 volt battery more than expected.
Scarlet Ember 2018 Leaf SL W/ Pro Pilot
2009 Vectrix VX-1 W/18 Leaf modules, & 3 EZIP E-bicycles.
PLEASE don't PM me with Leaf questions. Just post in the topic that seems most appropriate.