By quite active do you mean moving a lot, but at a slow relaxed looking pace? Or does it look more like "training for the snake olympics"? Also is it active during the day or only at night?

I've come to interpret the first as a secure feeling snake that might be out & about because it is hungry.

The second one, especially if it is out during the day, is more likely caused by stress. The best thing you can do for a stressed snake is to make sure it has snug hides available, then leave it alone (except for necessary stuff like giving it fresh water and taking it to the vet). If it is in a glass tank, or a more see-through tub, then covering the sides will help it feel more secure. Another great trick is to take balls of loosely crumpled newspaper and make a layer on the bottom of the enclosure. This will allow the snake to feel secure and hidden even when it comes out of its hides. Once the snake is settled in & eating, you can gradually remove the newspaper.

Also, you haven't posted details about your set-up. Make sure your temps and humidity are where they need to be!