And I am a proponent for this scenario, but the evidence doesn't fit.
Flash says "My name is Flash Thompson" and Sable responds "I know, and you don't have to hide the secret ID..etc,etc."
Soooo, this implies Sable thinks Flash is Spider-Man. When if the game has happened already, she'd know that wasn't true. And while that room might have been poorly lit, Flash and Peter look totally different. I don't think a pro like Sable would make this mistake.
Of course, it could be that Sable is simply extending a professional courtesy towards Peter and pretending to play dumb to not expose his ID to Roxxon or the Wildpack agents, but we'll see.