If it was a new aquarium I would try to exchange. If its a used aquarium, I think you are pretty safe. I have a similar tank(in my garage hasn't failed for several years) but I can't recommend wholeheartedly not worrying about it, any imperfection can cause a failure. Be very sure you tank is completely level, if you chose to fill it up. Maybe set it up in a garage for a few weeks, see what happens to the seam.