Just like what Pat said above, it could be taking in water. It could also be that it’s a light compsand and any weight added anywhere tends to be a more significant effect.
The multi fin boards I’ve made recently definately feel heavier in the tail loaded up with 5 fins compared to my normal thrusters but then they would. Time to look into lighter weight fins I think.
Probably not true with the Sunova…but I have picked up unglassed blanks (shaped and unshaped) with a very noticeable weight bias. Sometimes the foam goes into the moulds or expands unevenly. I recently picked up a blank that Mystic was working on because he said, “Pick that up and see if you notice anything.” It was very obviously weighted to one side, not even to one end. I think it was a Bennet, but I’m not totally sure. He was going to have to add resin to the light side to even it up. Pretty strange.