Head shape changed?

I have a weird question. When i got my super black pastel he was 60 grams and his head was very narrow.. and very unusual to me plus he was on the thin side. Well, after a month and a half with me and 6 meals later of adult mice he is 107 grams as of today and his head filled out a lot more and is wider right behind the eyes and looks more normal to me then before. Is this like a fat storage area or something? Was his head area behind his eyes so narrow due to being so skinny or dehydrated? Or is this supposed to fill in over time? Sorry but I was hoping his head would "fix itself" and it looks like it did! :D I guess I have seen adult Ball Pythons with narrower heads then normal but not as bad as my little guy had.

You know I don't knew if it is fat storage or muscle for the jaw but before thanksgiving my daughters rescued a very skinny Bp with a pretty narrow head and very skinny neck, he has put on a lot of weight but his head and neck have filled out the least, the neck folds have filled and hydration has a lot to do with that, his belly has got nice and girthy and I'm hoping that pulling his full belly around will build his neck muscle instead of just over feeding or him extra to put on weight fast and fatten him up. I also handle him often this might not be what the pros recommend but I think when he is crawling around on me or they have a climbing toy like a cat tower but for ball pythons. using some muscles instead of never getting any excercize in one of his hides
if given the option I think any animal would just like to not have to move and just have food delivered to my mouth (my cats sure would). but I feel alittle crawl around and stretch is good for them