Humidity spike?

How bad is a spike in humidity im on a bout week 6 of flower been keeping the humidity around 50 or below.
Last night my dehu turned off and it was at 80%!! This morning im hoping it was only like that a couple of hours or less

how bad is that?
Once or twice be ok?

You should be ok as long as it is not a prolonged or reoccurring issue

I've had a 12 light grow hit 82% for 4 days and the plants recovered after a really bad power outage. I was able to keep fans running but my Quest Dehumidifiers were too much for my generator. Definitely keep it in the 50s during flower to prevent risk of mold/mildew. 1 day shouldn't do anything at all as @ALPHA.GanjaGuy said.