I'll add my post to the group noting absence of such behavior. Not that that diminishes the issue OP experienced (it doesn't), but as a RCC/UC member for >10 years and as a 10 year 1K with IAD as my home airport for 4 of those years, I have never had a single issue with access or odd rules. Never once. A couple of times, the crowding at the C7 club led the door agent to suggest I go up to the International First lounge (surprise win!), but never anything like this.
I post only to frame the discussion, as bad as the incident might be, as an outlier.
Perhaps that C8 agent could turn her attention to the dog licking DJMURPHYNJ's shoes. or was that IAH....