Thanks for the reply! I guess you're right, but I expected to see the glass in the wrong location - sagging downward and away from the front to create a gap. In this case the frame is in the wrong location as it's moved too far forward and this resulted in a gap. So, I was wondering if it is the same thing.
Instead of silicone I would use black electrician's putty since it's waterproof and malleable and easy to remove when needed.
https://www.amazon.com/Black-Electrical-Insulation-Putty-pack/dp/B00O7S14U6