It kind of looks like it may have been over tightened. I would remove the lid and check for cracks on the lid and on the canister. I had my fluval 204 do this to me a few months back. Granted, it was old as can be and was made from ABS plastic, but it cracked after I installed a new, off brand oring. The oring ended up looking a little bit thicker and I thought, "oh, great, it should seal really well since its thicker." Um, nope, it ended up cracking the canister and since it was so old I could not find a replacement canister for it. That's when I bought a SunSun 303B to replace it.
Long story short, take the top back off, check the gasket and then check the top and canister for cracks.