It's possible, i didnt check each piece for being squre while being assembled. I'm baffled by it. I have a 2 foot and 4 foot level. Took my time checking everything when setting it up. I do like the stand that comes with the tank. And like I said the sagging i just found last week. The seam was what I seen before that's what bothered me.Mine doesn't do this either, weird, wonder if the top was warped and maybe you didn't notice? Can't imagine its sagging after the fact.