I guess I like living on the edge, lol. Have only ever had a problem once, and that was resolved with re-washing. If I have a fabric that I suspect might bleed - anything deeplly colored, but particularly reds, purples and blacks, I will wet them and rub against a white cloth. Thus far, I've had one maroon LQS fabric that needed washing.
To further my risky lifestyle, once that was washed, I combined it in a quilt with unwashed fabrics! In other areas of my life, I'm pretty much a rule follower, but in quilting - well, not so much!