My diagnosis says yes - someone who can affect the core probably needs to take a look at the skydome vertex structure at some point. I'm fairly certain this isn't a shader issue.
I've looked for this a couple times and never could spot anything wrong ... it probably requires someone to go in and strip out portions of the code to try to figure out if this a vertex problem, normal problem, shader problem, or maybe it's some subtle combination of multiple things, etc.
Thanks, Stuart! When I saw those nested loops in the skydome algorithm I didn't think there was enough coffee at Starbucks to fuel an investigation. Kudos!