Yes, a new disease, according to Valerie Scher of the San Diego Union-Trib: Excessive Ovation Syndrome.
The more people pay for tickets, the more susceptible they are to EOS, because ovations confirm that their money was well spent. Even those in bargain seats can easily catch it from their neighbors. The urge to stand and cheer may be irresistible if everyone around you is doing it.Read on. Scher is a classical music critic, but I'm sure you'll detect parallel symptoms.
Alas, EOS has no cure. But awareness is key to treatment.
I wonder how many of the standing end up doing so, like me, just to actually see the actors over the heads of the ovationists. Beats clapping in your seat looking at nothing.
I suggest a telethon.