Mine change colour depending on where I find them :). If they are on the top, usually nice red and round. If I'm digging down I can find some ones with flat bottoms (due to pressure), pale undersides on top of other stuff etc. As long as they aren't dead and seem active I don't worry.

If you've been doing mostly fruit, can you toss some crushed eggshells in, could be getting a little acidic. But can't go wrong with bedding, clean bedding is always an escape for them if something is wrong. When in doubt, bedding ;)

I put some crushed eggshells in a few weeks ago, but they don't seem to be going anywhere. I've also been putting in a lot of extra bedding to keep the moisture down. Thanks for easing my fears. :)

You may have two varities of worms, a purple/blue and a yellow flat tail. At different times one may have a greater population than the other. As long as they are all working for you. Egg shells never do seem to disappear. I can't figure out why the planet is not covered in them.