I came to the forum to see if there was a post about this, so... Yes, I am having this problem, yes, it's extremely annoying and as far as I can tell this bug plagues the majority of my habitats. Only a few animal species don't seem to suffer from it and weirdly enough some of them live in the same habitat as animals that do have this weird bug.
I also want to add that for some reason the quality of food doesn't appear in numerical order. I've had grade 1 appear at the bottom, at the top, in the middle, same goes for grade 2 and 3. Please fix this, because I want to give my animals the highest quality food that's available.