Would you be worried?

[Zylumn]

I just cut about 30+ linear of silicone d glass apart on a new tank and found a lot of it looked exactly like your picture. That is air in the silicone and I would continue to monitor, especially check to see if the inside silicone has air pockets. Also monitor if the air pockets get larger or if the glass ends that are fit together have shifted. It should not be a problem as it looks like a solid bead on the inside of your picture. edit ( ps air pockets are not the reason I cut the back of a tank)
Kevin