Is it normal that i had psoriasis only once?

Two years ago, I noticed a strange rash on my leg. A week later, it had spread to almost every part of my body. I freaked out and went to the doctor, who said it was probably psoriasis, and referred me to a dermatologist. The derm said it was psoriasis and that I should expect this as a lifelong condition. My best friend has psoriasis and hers is always there, but sometimes it grows/fades with stress. I started using the cream and it went away in another two weeks. I haven't gotten any rashes or dry spots since then. Is it normal for psoriasis to just happen once and then go away like that...like chicken pox??