I just started noticing that a couple of my brushes (chubby 2 and silvertip 24mm tgn) have soap leftover on the tips of the brushes after I use them. No matter how long I rinse and shake them out it feels like there's still a bit of soap left on the tips and as I let them dry, the tips get a bit hard until I give it a few swirls on my palm, then they soften back up again. I'm wondering, is this normal?