It seems fine to me, it's self-contained and it follows its own logic and defines the point it has to define. Plus there's hot off-stage sex, which is a plus. Casey is Casey, all Mr Spock on top (but no, that was another fan story from another lifetime) and all seething turmoil underneath. It's a vignette. Which sounds as if it should mean 'small glass of wine' but perhaps only in my head ...

Do you think it should be part of a larger story, is that what's bothering you? It could be a preamble to a Very Long Fic, but your plot pixies would know that better than I would.