I can explain the itch, Giant Sequoia used to be logged for their wood yet they soon discovered it splintered easily. Which explains why you ended up scratching your arms, some wood flecks got onto your arms when you hugged the tree. I'm sure other trees there may be safer to hug, try a Redwood or White Fir or Grand Fir you can hug them without scratching your skin off.
Awww you look so cute sitting there - like a toy Nate! That is one heck of a big tree..just saw some posts from a friend who was diving on a wreck off Malta - they looked like toy people too! I can see that you are a good person and this is a great shot!