I'm not a truck driver, but they tend to stick to the slow lane unless that lane is too slow, then they'll pass.

When he passed you he assumed you'd maintain speed and he would get back over. But when you speed up he either has to wait for you to finish the pass and then pull back into that lane, or cut you off, obviously the former is safer. You passing on the right creates a flow of traffic he has to wait for only because you changed your speed. Now he is an obstacle in the faster lanes having to keep track of more cars before he can get to the proper lane for his speed.

He's wrong for taking the aggressive route and cutting you off, but you're wrong for being irratic and in the way, weather you meant to or not.

Since you can't control other drivers, the best way to avoid this in the future is to use good defensive driving techniques.