Digital Crown casing fell off: How does Apple manufacture the digital crown?

After using my Apple Watch SE for 8.5 months, the casing fell off the digital crown.

There was no accidental damage, it just fell off when I was walking in a park. The function is still great - but without that ribbed casing, the dial won’t scroll easily anymore.

I spent an hour on the phone (very pleasant Apple representatives) but I'm told because this is uncommon, I’ll have to pay to fix it. Is the casing attached to the pin with glue? It seems like not enough adhesive was used in the manufacturing process - which should be covered by the manufacturer’s warranty.

(Apologies for the odd pic. This was taken before I noticed the casing was gone.)