Whatever happened to my good little eaters?

The boys have become increasingly more difficult to feed over the last week. They start off okay, but then half-way through their feeding they begin to push their bottle out of their mouths with their hands. Then they scream because they want it back! I read yesterday that this is only a phase and that they should stop doing it in a couple of weeks. I've overcome the challenge of feeding two at the same time, but I guess they can't make it too easy for me! ; )