This is one I've done before and apparently haven't learned from, so maybe you will learn faster than I do. Yesterday I caught an 8 lb blue cat and had to use the pliars to remove the hook. When I did, I thought I might have pinched or nicked the line right above the hook with the pliars, so I checked it and found nothing obviously wrong. WRONG! The very next fish was very large and I could barely move it - usually means a 30+ lb fish - and after a very short time the leader snapped right above the hook. I had obviously damaged the knot or the leader, and because I didn't take the few seconds to snip off the line and retie the hook I lost a big fish. It is amazing how a very small nick can severely weaken your line. If you think it could possibly need to be retied, it does!