I have gone 30+ days without dairy (except for GF butter and ghee). Yesterday and today I had a slice of cheese to see how it would go. I don't know if it's related, but I felt wonderful about an hour after eating it. I had energy to move for the first time in weeks.
I can discern no negative effects from doing this. Is there a reason why I shouldn't eat it again?
Based on your story, your response certainly doesn't make the case that you shouldn't eat it.
Thankfully, the issue of dairy and paleo has received a needed injection of complexity. People like Chris Kresser and Mat LaLonde have begun to complicate the discussion about dairy in a way I find illuminating. Check out this podcast to hear their discussion on the topic:
Take a drop of the food in question (if the food is solid, mash and mix with a bit of water) and place it on the inside of the wrist of the patient. Do it at bedtime. Let the drop dry on the skin, then let your patient go to sleep. In the morning check the spot: if there is an angry red reaction, then avoid that food for a few weeks, and then try again. If there is no reaction, then go ahead and introduce it gradually starting from a small amount.