Strange white powder inside willow sticks?

[Lone_Cosmonaut]

I bought a stack of Woodlands willow sticks at Pets at Home for my dwarf hamster a few months back. He never took much interest in them since he's not a big chewer, but I've always kept them in his enclosure just for decoration. However last night I noticed he had begun to chew one of the thicker sticks, and was alarmed to find that the inside was filled with very fine white powder. I took it out immediately and snapped a few other sticks in half. They were just regular wood straight through. My sweet little boy seems to be okay so far, and it didn't look like he actively sought to ingest any of the powder ... But I'm still worried sick, and was wondering anyone could tell me if this is normal or safe ...