Default gallery style - did something change?

I'm wondering if I missed an announcement...

I haven't spent too much time in my smugmug site for awhile, but visited today trying to find an old photo. I had almost all of my galleries, with a few exceptions, set to use the Smugmug gallery style. Today I noticed that almost all of them now appear to be displaying in a collage style.

This wasn't a change I made. Does anyone know what happened, and how I can get the appropriate galleries to revert back to their original style?