Oh, I'm glad to hear that. I've been pretty surprised by the lack of interest in the movie from other people I've talked to. It's like they didn't grow up with the Muppets or Sesame Street or something like that. I can't explain it otherwise.
I know that The Muppets were on things like SNL and other sorts of stuff originally, but The Muppet Show was first shown in the UK and then syndicated worldwide. I guess it sort of explains why there were a surprising number of English-based guest hosts. So, Muppet-fandom runs deep in the UK!
Normally it's due to publicity requirements. Getting that all-important interview with Kermit and Miss Piggy and all of that. And it's only as early as it is to qualify for BAFTA submissions... without that, it could have been released any time afterwards!
It's not a spoiler. It's the first song in the film and doesn't really reveal anything. It's just so happy and joyous and wonderful. I'm listening to it right now for what must be at least the 50th time!