My homemade forge handle snapped mid-swing, nearly took out my grinder

I was finishing a damascus billet on Wednesday around 5pm when the ash handle on my 4 pound cross peen let go right at the head. It wasn't even a strike that hard, just a normal hammer blow, but the wood had a hidden hairline crack I never spotted. Broke at the tenon like a toothpick and the head flew across my shop, dented my 2x72 grinder's platen. Lucky it missed my leg by maybe a foot. I've swapped to a hickory handle with a steel wedge, but now I'm second guessing every tool I got from my old stash. How often do you guys replace or inspect handles before they fail on you? I never thought one would go without warning like that.