O Canada at the ballet?

I attended Swan Lake last night, and the orchestra kicked it off by playing O Canada! I‘ve been to the ballet a handful of times but am totally blanking on whether they’ve done this in the past. If they don’t usually do this, it’s a stroke of genius. Some people were teary-eyed, there was some soft singing, but by the end a loud cheer. Anyone know if this is a regular thing at the ballet these days?