Yes, that's just what the glochids look like when emerging. A helpful thing to realize about cactus is that they generally grow in the summer, while most of the plants surrounding it do the opposite.

Im late but this just happened to mine and this is the only post I could find that looked like it, except mine only had the white mold. Yesterday I did my routine poke check to make sure everything's good and It was perfectly fine, today I walk past it and noticed it had mould all in the cracks of it, I pushed a spine and it cracked open and was full of mush. Cant figure out what caused it either, had it for years and it survived a mealy bug attack and everything. Now I'm on a mission to find another one...

It looks like the brown part at the end is dead. I would cut that off and fill this jar with water to give all of the nodes a chance to take root.

Normal growth