coil on plug boots

I just got done changing the plugs on my '00 gt and had a fun time with the boots coming off the coil and leaving the spring dangling out the end.I wiill assume that this just happens and it is ok becuase i finished up and she runns fine.Also a on ford build quaility as i am the second owner and the car had 25,000 miles when i got it.I found the two plugs by the plenum opening where burned up on the out side to where the metal was flaking off the side of the plug.I have to assume these where the original plugs they wher motorcraft platinum 32.