That sounds like millipedes or centipedes, one of which (I forget which) you don't want in your bin.

Centipedes. Oh god, I am sufficiently freaking out right now. Any idea how to get rid of them?

From my understanding hand catching is really the only way to deal with centipedes. Just make sure you handle them with gloves or a cup of some kind as they do bite. I came across one in my bin about a month ago, luckily I didn't grab it. A few weeks later I was digging around in my bin and came across a centipede again,don't know if it was the one from earlier, but since I had waterproof gloves on I picked it up. I could see it trying to pinch the glove. I haven't seen another one since but I am not foolish enough to think there might not be others in there somewhere. Still have plenty of worms and the population seems to be growing so if there are more centipedes in the bin, they aren't decimating the herd too badly.