This was our old tank, and if I recall, those bubbles have been there since we had the tank set up, 2+ years ago. Since we never let the tank set dry, between when we stopped using it and it was picked up, that should have helped maintain the integrity of the silicone seams. We know how larger tanks don't always do well when left to sit dry for extended periods of time. That was why we took the extra effort to keep it wet/filled (to about 80%, about an inch below the bottom of the overflow). So I am not sure of how much concern they would be, but it doesn't hurt at all to contact the tank manufacturer about it.