Not unusual at all for Belgian beers. If you have a chance get and read Brew Like a Monk. It goes into great detail about bottling with fresh yeast. They do it for flavor profile and to help carbonate the beers. The beers this is used for are usually bottle conditioned for some time. The fresh yeast helps that process.
"Look, let me explain something to you. I'm not Mr. Lebowski. You're Mr. Lebowski. I'm the Dude. So that's what you call me. That or His Dudeness... Duder... or El Duderino, if, you know, you're not into the whole brevity thing." -The Dude