I just set up my new Aqueon 40 gallon breeder today and I noticed that the glass hood isn't flush with the center front part of the frame. At first I though the hood wasn't cut right. However, I measured and the center of the tank bows out 1/8 in. It really wouldn't be visible if it weren't for the hood. I don't have it completely full; the water level is about 2 in below the top. I can definitely take out some more water if that will resolve this. I found some old forum posts saying that this is common and not cause for alarm but I wanted to check in anyway. ETA: Out of curiosity, I decided to go measure my 10 gallon. Lo and behold, that one also bows 1/8 in, which is proportionally much more in that tank than the 40 gallon. It's been up and running for 3 or 4 years now so that's reassuring.