I was very disappointed when the Big Al's stores around here all stopped pushing/selling Miracles brand tanks (an excellent canadian domestic brand for you non Canadian MFKer's) in favour of Perfecto ones. they are the cheapest ones out there. and cheapest for them to buy so that why they mainly sell them

. but other than their 'deep dimensions' line of tanks, the build quality and quality control on some of these tanks is not that great.
I had to special order my All-glass (aka Aqueon) tank because they don't carry them, as they are more expensive (but much better built)
problem is, the average fish person doesn't care about build quality- they want the cheapest possible tank. if a well made 120g is $300, and other not so well made brand is $250, guess which one the average person buys?
it sucks. note I am not saying you were like this, it just sucks that the mentality at Big Al's is to make the cheapest made tanks the most available.
sorry for your bad luck. either way, something needs to be done because the ends of the tank are where the most support is needed (for glass tanks).
if the gap were in the middle of your stand, but the ends were well supported, you would be fine. however, it appears that the ends are floating, and the middle is supported which is a bad thing.
I would try and speak to the dry goods manager at the store where you bought the tank, explain the whole situation and see if they can help.
good luck