The filter bacteria are a lot more robust than people realise. It does take quite a long time for them to actually die; they become dormant first. Because you switched back on within a few hours they shouldn't have come to any harm. I had a planned power outage last year for 8 hours, and your filter won't have been off much longer than that. I have also forgotten to turn the filter back on after a water change and only discovered it next day without anything happening to the fish.
It is common for filters to spit out gunk when turned back on, you'll remove that during a water change. Your ammonia and nitrite had risen as the water wasn't going through the filter and the bacteria on the surfaces couldn't cope with all the ammonia the fish made during the night. Once the water started to circulate back through the filter, those bacteria would have started to do their job.
Keep an eye on your water for the next few days just to be sure, and feed the fish slightly less than normal (less food = less ammonia). And water changes if the tests show a reading over zero - hoover up the filter gunk at the same time.
And ask Santa for a timer for the lights