I use coco-husk. Never had a problem - we used to use aspen and our Orange Ghost got a piece jammed in the corner of his jaw so we try to avoid wood shavings now.

It sounds like the mouse was too small for your BP. When we feed our little guy he's gotta stretch his jaw out so far than any substrate (at this time aspen) that was stuck to the feeder fell off when it would get to his mouth.

From what I understand BP's are able to digest the wood shavings so I wouldn't worry. Its not something you want them to ingest because it was cause internal issues as aspen is very sharp - but the wood is in there so there's nothing you can really do. I've had snakes eat it by accident and be absolutely fine. I would just recommend switching substrates for the future.

Cheers