I would say it depends on how the job was done when it was subbed out. I'm assuming that the sub billed the GC, and the GC took a markup on the sub's bill. That's normal, but if I'm working for a GC and billing him and he's taking a markup on my invoice, I shouldn't have to deal with the HO at all.
That doesn't normally happen as most GC's are out to lunch when it comes to electrical, so it's easier for me to discuss wiring with the HO directly. If he's getting a cut on my invoice but not doing any of the legwork, I'd say it's fine to go back later and work directly for the HO.
