I put a coat of Evercoat Z grip on yesterday, and came back and sanded it today, and noticed that the filler seemed a little softer than I remembered it being before. It started curing after about 5 minutes or so and cured out and everything, but it just doesn't seem to be as hard as some of the filler thats been on there for a month or 2. You can press your finger nail into it hard and it will leave a little place...maybe Z grip stays a little softer? It never gumed up on the sandpaper. I've used it alot before but I cant remember how it was then because Ive had the filler and hardner for maybe 6 months and only used about half of it. I was just wondering if filler hardner ever goes bad?