I've seen similar, I'd never had trouble just running the drill till the sides were smooth before, but some of these sticks were still pretty live, and no matter how long I let the drill cut into the sides, or what speed I used, it still produced fluffy sawdust and left those splinters along the inside of some. I'd been planning to wait a year on those and drill them again but it took more sticks than I'd planned to fill it. For what it's worth, they're pretty soft, but they might harden as they dry? If it's a legit risk for the bees I'll definitely pull those tubes. I think cardboard tubes are probably the better way long term, certainly they're less work which would make replacing them easier. I just prefer to make things myself when I can.