Not so much in bass fishing, but regardless of brand, I have seen quite a bit of more "mystery breaks" on 30 lb than 40 lb braid. That being said, sounds like in the OP's case, the line is defective or compromised in some way. I would switch out reels to a different rod and tie something worth loosing to both to help diagnose. Small nicks in light braid can really weaken it, (you'd think it was fluoro)...