I changed the spark plugs today on my 2000 STS. On the front coil pack, one of the terminals has a crack on each side of the plastic. It's not too large, maybe 1/4 inch, but I'm not sure if this is something to be concerned about? The terminal doesn't feel loose, so I'm not worried about it falling off, but I'm not sure how the crack got there to begin with!
Any suggestions? I thought about maybe adding some glue to help stop the crack from spreading.

If I had the problem I wouldn't worry about it and would probably put some glue on it. Make sure you don't get any glue on the terminal.