I know some Betta's flare alot, but wow! Mine does not stop! I got him around Sept/October, after Mint from Petsbarn. Ok, first bad sign is they had the poor Betta's in their cups on a spinner, like you see for Jewelry at the stores. Then, I was going to split a ten gallon and have my boys in that. "Flareboy" which didn't have a name at the time, got his name because he would flare non stop at Mint, they weren't even in the same water! Just next to each other, so two days of that, I gave him his own 10 gallon!
Even just this morning, walking by his tank, there he goes! He is currently on the Kitchen counter until I get his stand up, and we cant put anything new by him or he flares. He flares when I open the tank, he flares when I drop the food in, he stops flaring and eats,then FLARES! Lol. Poor thing, he even attacked his filter when I turned it back on!
Just thought I'd share something about him! Since I'm always asking about Mint

Here's a blurry picture of Flareboy- in action-lol. (I'm getting a camera soon don't worry lol) He is all black with a little blue in his "tail". The bright "white" section on his "tail" is the blue :)