Can be potentially dangerous. My 40gal tank bowed about that much and before I knew the seams of the silicone were wearing out. I took my whole tank apart and just for the heck of it, I filled it up again (outside of course) I noticed that the seams got even weaker. I think it really depends on where the tank was located in the LFS
you got it from. The one thing I noticed that was my tank was always out in the sun at the LFS
...I'm not sure what the sun can do to silicone but I would just check the corners of your tank to see if there are any airbubbles. My tank didnt have any airbubbles at all until it was full, and once it was full airbubbles up the @ss. IME
, I had a bad tank, but yours could be perfectly fine.