That does not sound like too much light, even that close to the surface. In my experience, Xenia is good at adapting to various light levels. They stretch tall when they want more light and they stay short when they have too much light. So that is a good indication of what they want.
On the other hand, if they are a new addition to the tank, it is possible that they weren't able to adapt quickly enough. In that case, you should move them down to the point where the light intensity matches were they were originally at the store.
What kind of Xenia is this - Pom Pom, Elongata, or other?