Would it count as relapse if you viewed slight amounts of P in a dream??
Nothing in a dream counts as a relapse. Unless you can control your dreams which is a different story
If you dreamt you were binging to PMO, it is not a relapse.
It also means that if you woke up and had a nightfall/wet dream/involuntary ejaculation, it is not a relapse.
It was unconscious behaviour beyond your control. The goal is to remove these behaviours from our conscious waking lives.
Dreams like this happen to us on this journey. @Adioz gave some good advice on what to do afterwards.