Personally, I wouldn't worry about it too much. On a long solid wall with no windows or doors, you have nothing but 2x4's running up and down, that wall in a big wind is going to flex some. I have one wall that is nothing but a solid wall. It will flex some when we get 40+mph gust. Winds like that can uproot trees in wet weather or snap limbs when the leaves are full.
Are the inside of the walls finished off? If not, cover that wall in plywood or OSB and run the sheets horizontally. Insulate before you do it just to have it done though. The OSB and even drywall will strengthen the wall up. Even though you have T1-11 on the outside, the sheets are running top to bottom where you don't have the strength. Horizontal mounting of OSB or drywall gives you the strength.
And if it's been there for ten years, this isn't the first time it's happened.