Once you put weight onto the stand you may not see that 1/16 difference anymore, because the wood will settle a bit. You said it is in the middle? Can you sand it down any? IMO
you shouldn't have a problem if the stand is built to hold a fish tank.
Edit: Just looked at the other thread. I wouldn't put a 50g tank on that unless it was built up on the inside to handle that stress. Most dressers I've seen can't deal with the weight you are going to be putting on it.