I think it’s because the battery cover clip in the photo has been squeezing the hose too hard, so I’ve left it resting on top of the clip. I’m not sure how serious this is. Has anyone else encountered this?
Are you sure that’s cracked? It looks a bit like glue residue from either a sticker or some tape that has long since fallen off. Have you tried running your finger nail over it to see if it comes off?