Yes. They are fine. That bluing is normal. The only thing i would be concerned about is those mushrooms touching the wet perlite as perlite is hard to keep bacteria free.

Here is what cobweb mold looks like on a cake: http://www.shroomology.org/uploads/post-1-0-23889100-1347632262.jpg cobweb grows quickly, in a matter of a day or two. It is very obvious that you do not have it! Good work.

Perhaps one suggestion is to raise your cakes higher off the perlite if you can to prevent infection in general and allow a little bit of air circulation around the base of your cakes. You dont want water pooling and touching the cakes or your mushrooms as that will certainly lead to an infection of the cake eventually. A potential way to do this is to put a mason jar ring or something else in between the foil and your cake to raise it higher off the perlite.

Another suggestion for the future would be to omit the perite all together so that you can disinfect (i.e. alcohol sanitizer, bleach spray, etc) the whole tub in between flushes while you are dunking your cakes. A good substitute for perlite is a small bread pan/small bowl with a couple waterlogged sponges in it, complemented with your misting of the walls of the tub daily. The sponges and bread pan/bowl can also be easily santized periodically with bleach water much easier than perlite, therefore decreasing the chance of an infection a lot. Water will evaporate off the sponges into the air but will also never pool around your cakes. Sponges do not work as well for relative humidity but they do work.

If you smell any mildew in the tub when you open it, you know you are going to have a bacterial problem. If the air in the tub is generally fresh and faintly mushroomy, you know all is clean and healthy.