If he is like my Malibu (who discovered AC in the middle of a humid Southern summer) he will know which side of the door has the heater on!
Expect him to stay longer and longer.
Dusty (barncat) also comes inside now. He can stay in all day or all night, but he has to be let out because he won't use the litterboxes, he prefers to 'go' outside.
Pretty is a former feral, who is holding onto her feral ways, and while she will let me pet her and hold her for short periods of time...she does not feel comfortable in the house for very long. However, my husband tells me that twice this weekend, HE has let her come in and she DID come in. I think that is a fabulous step for her to take, accepting Hubby and coming inside. Maybe she will spend more time inside this winter.
My barncats may all become housecats.