NS are good club players. South has just returned from a year of no bridge. This was his first session. EW are perhaps not quite as good, although East, who is generally argumentative and intimidating at the table when he feels (rightly or wrongly) there's been an irregularity by the other side, would probably disagree.
When South bid 4♥, West asked if there'd been a failure to alert. South said "I'm not sure". West and North Pass. Now East chimes in "If 4♦ should have been alerted then I want to double 4♦!" And he puts a double card on the table. Director! She has difficulty getting East to quiet down. In the course of "discussion" East asserts "of course he knew it should be alerted! He bid 4♥!" Rather loudly, too. I heard it, on the other side of the room. In the end she requires the auction and play to proceed, which it does as shown. 5♥ making was an average board. No further director calls ensued.
How would you have handled this one?