I say they are either rootbound or overwatered most likely rootbound, mine look like that when they get rootbound although you seem to have a pretty decent size pot for plant size. right after you water loosen the soil from the pot by squishing the pot a bit with your hands on all sides flip the pot over and take the soil and plant out of the pot and check its roots, if you can just see some here and there it is ok if they are all over the place and swirled all over the bottom you need to repot.