It makes sense that it could be the tighter control causing you an issue. I'm at the same stage as you with the pump. I feel like I'm having fewer hypos, and less severe, but I don't know for sure. The research data says "fewer hypos at no cost in HBa1c".
Your gardening incident is odd though. If that happened to me I would think something had gone wrong at mealtime. Too much insulin, double dosing, or a tummy bug. To go from 11 to 2 so quickly.
One thing we were told in a follow up pump class is that there's a delay of a couple of hours when you change the basal rate, before it affects the insulin in your bloodstream. That it's slower than a pen injection I guess. That surprised me.