Mine came with the flex type on it already. What the dealer didn't do is remove the shipping protectors from the wiper blades. And I never did either. Good thing they didn't scratch the windshield when I used them. I actually used them through an entire rain storm before I realized the next day (after thinking they didn't do very well) that the shipping protector was never removed. Kind of embarrased to admit this, but maybe that is what is happening to you???
Wow we'll don't blame yourself for it, the dealership should have done it during the pre delivery inspection. Thankfully your windshield didn't get scratched.