[matthew chung]"s there a way to avoid this using the LCD?"
Avoid using higher picture gain settings during low light shooting. That's probably what's causing the noisy picture. Checking for fine detail issues using the camera's LCD is not a good practice because there's not enough resolution. You need to use a good quality monitor while you shoot. Your computer monitor should provide a more accurate picture.
Like Don said, I'm pretty sure you had your grain cranked too much to get more light on your image. A trick you can use to see if your image is really grainy using the LCD is to push the 'peaking' button, which is just below the 'display' button. It's used to check your focus, but will give you a pretty good idea of how grainy your image is. I'm sure you know this, but also make sure you shutter speed is at 1/50 and your iris is at f/1.6 at your widest zoom.
The medium gain setting on the on camera toggle is 6db, but you can get to 3db if you go into the menu if you need to.