As you know, a grand total of four House Republicans voted on Friday against Paul Ryan’s plan to end Medicare as we know it. But now we’re discovering why they voted against it — a couple of them worry that the plan will force seniors to pay far more for their medical care, which is exactly what Dems are claiming.

Here’s what GOP Rep Dave McKinley of West Virginia, one of the No votes, had to say over the weekend:

“The Congressional Budget Office determined that some of the out-of-pocket costs could double for seniors and that sent up a red flag for me that we need to look at it,” he said. The Ryan plan does not affect people who are already on Medicare or anyone who is currently 55 or older.

But McKinley said Ryan’s plan made him “uncomfortable” because people that would be enrolling in Medicare just over a decade from now might not realize the costs they would face as they retire. “I think we can do it another way and now I’m going to be curious to see what the Senate does,” he said. “I want to be an independent voice here.”

Meanwhile, GOP Rep. Denny Rehberg of Montana, a second No vote, was quoted this way by the Great Falls Tribune: “there are still too many unanswered questions with regard to Medicare reform, and I simply won’t support any plan until I know for a fact that Montana’s seniors will be protected.”Rehberg’s state has a disproportionately large senior population.

No question, the GOP was able to maintain an extraordinary level of unity behind Ryan’s plan, and it’s unclear whether that unity will fracture once negotiations between the parties get under way in earnest. But it’s certainly interesting that a handful of Republicans have now asked whether the Dem critique of the proposal has something to it, and this will be a dynamic worth tracking when start making good on their vow to use the Ryan proposal to campaign hard against vulnerable GOP incumbents.