Good observations.
I can tell Jewel is slowly getting a bigger head. I will re-read the coastal section in THE COMPLETE CARPET PYTHON and see what I find. I could swear there was a part about a certain locale of coastal that had flatter heads than other species and maybe other coastals.
I think they get wider as they age. 3.5 years is still very young and I think she is still adding length.
Keep me posted on what you see as your animals age!