It is hard to see in the pictures but I do see the new growth looks flat and very pale..
It could be... Try to think of your plant in terms of Troubleshooting. Is it getting enough light? is it getting enough nutrients? If you answered yes these questions. You need to start too look deeper... Root rot or being rootbound can display in a number of ways. How's the moisture of the medium? Does it feel wet all the time? Lift the container of the plant, you should feel differences in weight daily as the plants takes in more water. Always try to remember those roots need air just as much as they need water. I hope this help and happy growing.