Virtua Fighter 5 1080p Bug?

I just received my order of Japanese PS3 Virtua Fighter 5. Now I have 5 PS3 games, and this will be my first 1080p game.

When I started playing, my Aquos LCD TV indicates that it is in 720p. Even though my TV supports 1080p, VF5 would not show 1080p. I checked firmware update and PS3 settings but I still could not get 1080p. After I tried a few things in display option, finally I figured out the way to get 1080p. You need to uncheck 720p and 1080i, leave only 420p and 1080p checked. This will allow you to play VF5 in 1080p. When you want to play the other games support only 720p, you would need change back the display option.

I am assuming it is either a bug or VF5 native resolution is 720p.