Here's the kicker to that recall: if you read the fine print, it's only the aftermarket brake fluids that cause the issue. If you maintain your car at Toyota and use Toyota brand brake fluid, you're fine, no issues. There's some sort of polymer in the Toyota fluid that prevents the problem by lubricating the seal, and when people start using off-brands, they don't have the polymer in them, and the seal dries out. I always say maintain your car at the dealer (especially when you hear Jiffy Lube horror stories!)...here's a good reason why.
On the Sienna: not every model uses the same components, so no reason it should be involved in the recall. It may just be getting old, unfortunately...