Sounds like he was a little feisty. It could of been from being hungrier then normal, saw a reflection, saw a picture of another betta at some point that day, the chemistry being slightly off, possibly even was in the "mood" and was hoping a female was near, etc.
As for wanting a larger home.. they have no concept of such things like we do. They are in massive breeder tanks, moved into jars, then cups, then we take them home. They have no idea/memory of space such as open tanks, or in the wild. They accept what they are in as normal/home. Some even fear larger tanks when moved to them. They aren't going around thinking "I want a bigger home, I want a 5gal tank" etc. They don't have the mental capacity to think that way. A 2.5 gal home is a great size for them. You can go larger if you wish, but don't think his acting feisty was due to him wanting a larger home. Others should realize not everyone can afford to buy big tanks for each of their bettas. Yours just was in a mood.