That's good
I have a leo that I bought from a petstore that has that same proportion. Her tail stays at a constant thickness and she obviously stores her fat in her midsection. She is a little small for her age, which we're trying to correct, but she's always been chubbier in her torso. I guess geckos can be like people, we all gain weight in different ways.
Just make sure you watch that waist line
