I've noticed that my new brush has started to dry strangely...the tips will be hard and kind of crispy, which I don't understand as I rinse my brush really well. I even used a vinegar water solution last night (let it sit for a few minutes, rinse and dry) and then today after I used my brush, it dried crispy again. It's one of whipped dog's silvertips, 24mm. I've never had this happen with any of my other brushes. What should I do?