Is my cactus sick? or just pretty?

i bought a cactus about 6 months ago. I don't know what type it is, but it is a barrel covered in little nub things about a cm long. its pretty small, about 4in in diameter. About a month or two later I noticed that there is an increasing amount of fuzz growing in all the nocks and crannies. There was previously only really on the top now its everywhere. I also noticed that the soil retains alot of moisture. But it is planted in cactus mix, lava rocks, and sand. I had my dad put 3 of my cactus outside including the problem child when i went on vacation for 3 days. He made sure that it didnt rain when they were outside. I live in southern pa, so during the day its about 70-75 degrees, and at night 55-60. I come back and there is a lot of white fluff all over if and its completely pink not green. None of the others had problems. Ohh and it was south facing. Is it sick??