Did you put the green rubber gasket on correctly that goes between the tank and the lightech aluminum base? There is a slot where the gasket goes only one way. If you did line this green gasket up is likely shifted when you turned the aluminum base upside down to install it. I put a very very small dab of glue in 2 or 3 spots to hold the gasket in place while upside down. I agree though it should be a little more flush than that. Your green gasket may also be upside down causing excess clearance...but I agree it looks a little off.
Try what I suggested and let us know