Oh, yea, mine did that too. Hate it! One tank, it was small enough that I was able to fill in the gaps with silicone. On another I used sphagnum moss. Another got clay smooshed in there. One of them got the background torn out.
When you use great stuff, it really takes about 2 weeks before it is done curing and shrinking. Shrinkage is inevitable and every few days after the initial application, I just give a good squirt where it shows visible shrinkage and it really helps to prevent shrinkage over the long term.
Also if you put a thin layer of silicone down on the glass before the gs, it does not peel back quite as bad. I also add gs periodically over a week or so as mentioned above, it gives you a chance to plan your hardscaping instead of just randomly squirting gs and hoping for the best..
Alright. It was only on the very top and the right right. The left side I sealed when putting the silicone/peat on the gs, which I didn't mean to, but glad it happened. It's not an issue on the back, which is where it can get bad, but I had that ha[[en twice where it feel off entirely.