Cody - the tank is probably not cycled in 1 week. The ammonia and nitrite that will build up in the tank will burn the axolotls gills, and cause undue stress not to mention its just not good husbandry.
If the tank they were in originally has been set up for more than a month, put them all back into that tank until the new tank cycles. Tank cycling takes usually around a month or more.
There are a lot of old posts on tank cycling, you may want to go back through the forum and read them.
Heating a tank to grow gills is a questionable practice at best, since axolotls enjoy cooler water not warmer water, and I really don't think heating a tank will make their gills grow.
Keeping good water quality and giving good care is the way for your axolotl to have the gills it was meant to have naturally.