Because it's always using a little bit? Some programs purposefully use swap for data they need to be in "ram" but don't need fast access to. (I'd bet the torrent client is doing this.)
The OS may also be intentionally swapping unused or infrequently used pages preemptively, since it doesn't know when you will suddenly open up After Effects and need 20GB of RAM in a hurry.
You can disable you swap file, but that can be dangerous.
Anyway, check your Resource Monitor's RAM tab and look for hard faults. If it's zero or close to zero, then you're not really hitting your disk for anything and it's just Windows being fat and stupid. If you have the disk space, don't sweat it.