taking in and outside is opening a can of worms for you,yes that is heat stress,put your hand on the top of your canopy,if the heat from the light is uncomfortable to the back side of your hand move light up,i also run 400 watt light,when i was veging i kept mine at 20 in from canopy,66 days of veg you should be flipping lights,what strain you got and how tall is plant,keep this in mind if your plant is 2 ft tall now when you flip it will streach about another foot and up to 1 1/2 foot for some strains,when i flipped mine they streached 2 ft,my girls stand 5ft tall in a 7 ft tall room add the filter fan combo and i have 6in in bettween my tallest bud and filter.just keep that in mind ,putting plants outside and bringing into a grow room is asking for all kind of bugs.this is just my opinion based on my grow so i hope i helped you out