I would suspect that is good news. Hay is the primary way to keep those ever growing teeth worn to a proper level. Contrary to what many believe, it's not how hard something is, but how chewy it is that helps wear the teeth. In a rabbit with proper dentalocclusion (the matching of the upper and lower teeth) the teeth are worn by tooth to tooth contact...and that is what you are hearing. Different types of hay require different mechanics of chewing...so it wears the teeth better. I love to hear the crunch going on because I know that is benefitting those molars. And if you will notice, your rabbit doesn't crush food with an up and down motion...the molars are curved and a rabbit chews from side to side....they actually fold the hay into something that looks like an accordian. Long stemmy hay is excellent for folding so it works those teeth quite a bit and the gut benefits too. All of our rabbits...including our wild cottontails in rehab...all receive unlimited amounts of different types of hay. Keeps them busy, allows them to forage more naturally and all that hay keeps good teeth and a happy gut.
Randy