Your plant looks completely healthy and I see no problem at all. Typically when the extension/height between each petiole decreases, it is a sign that it will either bloom or occasionally needs some fertilizer. In the case of your plant, I would expect a bloom pretty soon, which of course comes after a flag leaf.
This is what Banana Bunchy Top Virus looks like:
It seems there is an epidemic lately of people thinking they have BBTV here on the mainland. It is fairly common and very problematic in Hawaii, but rarely is found here in the US, even in Florida. I actually don't know of any cases here because the insect that transmits it doesn't live here, the Banana Aphid.
I hope my information above is all correct, but I'm sure someone will let me know if it isn't.