Ended up with a slight headache towards the middle of the day today. 
More than likely it was due to not having enough water while hiking in the heat. But it could possibly also be stress/tension related too because we were hiking slower than I'm used to and it was starting to get on my nerves especially when dealing with situations that get me worried/paranoid. Like someone getting seriously hurt or something.
Thankfully taking a bit of Excedrin seemed to help get rid of it for most of the rest of the day. I can feel it creeping back up on my right side again, thanks again to tension and being around too many people today.