That's great news on your update. I have a 4 yo Mustang that I just got in Oct. He was a solid, quiet boy...never know he's a Mustang. But the cool weather combined with some herd changes, he became quite spooky. In fact he bucked me off 3 weeks ago when someone reprimanded him while under saddle (they used too much pressure and should have allowed me to do the correction but they meant well). We have been doing lots of ground work and he has settled in. He's the leader and has more confidence but still occasionally gets worried on those more drastic weather changes such as sudden gusts of wind, quick temp drops with rain, etc. I have to keep him on a regular training schedule and I work him everytime I see him and he's doing well. I have a trainer I work with too (I was training with her with my last horse), and she helps me fill in the gaps when I need help. Kudos for enlisting the help of a trainer and wish you the best for continuued success!