I am painting a very old house, probably built in 20's. It is used as a youth program house for a YMCA in our neighborhood. I am painting all the walls with Super Paint satin, two coats. After three days, I noticed a few spots which had bubbled in one room. I have seven rooms going right now. They looked like nail pops. The walls have been painted several times as you can imagine, and I'm not sure what was used previous to my involvement. So, what do I do to fix these bubbles? I read that moisture may cause them, but no other areas have them. I tried to search this topic, but I must be doing something wrong. I am sure this topic has come up before. Thanks in advance.