My puppy is shivering but his whole body is warm?

Yesterday my shih tzu got a really short hair cut all around his body except his head cause he just got a trim on his head and when we came home he slept most of the time. When it came night time he came to my bed to sleep but he usually doesn't but i think it's cause he was cold or something.So then this morning when i woke up he was shivering and then not and it was a pattern. So then i took him on his daily walk and when i came home i went to see the temperture in my house and it was 74 degree's so then i changed it to 78. Do you think he was shivering cause it was 74 degree? Also he wasn't shivering badly , it was just a minor shiver.