Mine also had one tab out of the slot, from the dealer. Apparently since it sat that way for a while it warped the plastic slot downwards and wouldn't let the "nail head" go into it deep enough so it could slide back. Similar to what Cannondale recommended, I adjusted the plastic by bending the slot sides upward gently/slightly. I used a hair dryer to help it. Additionally, I had to exacto-knife trim the 45 degree edge, on the hood, adjacent to "nail head" back about 1/32" because it was hitting to hard, also not allowing the "nail head" to go in the slot. This isn't something I'd recommend unless your sure it's an issue.
I'd still take a fighting a piece of plastic over replacing donuts or y-pipes any day...