Is a day off from a diet a 'bad' thing?

So I've been dieting and working out for a month now so far. I run for an hour every day. Today, my muscles were very sore, so I took a day off. I ate clean the whole day until dinner where i also had dessert (which I don't normally do, but i don't want to restrict myself).
Is a day off okay? I feel a little bloated because of eating other things that I normally do :(
Is a day off from a diet a 'bad' thing?
Post Opinion