a set back with refinements?

I have 14 refinement trays left. I originally had a diastema, and my first set of trays corrected it, although the result wasn’t completely perfect. However, I’ve noticed that my diastema has opened up slightly again since starting the first refinement tray. I’m not sure whether this is intentional as part of the treatment plan, perhaps to close it properly later or if it’s something I should be concerned about.

Did anyone else experience this?