Brewers - Batter's Interference?

[SC Ump]

I only saw the replay on Sports Center so might have missed something. Anyone have further info?

In the Brewer's game on Friday, Clark was batting. He swung at a pitcher. PU called time, gave a signal similar to foul tip and then stepped up to Clark, giving an out signal and I read his lips to say "batter's interference." ("Batter's interference" is also what the announcers were saying, but they don't seem to be right too often.)

I replayed the Sports Center piece and could not see a foul tip occur, the bat hit the glove or the back swing hit the catcher. The batter did not seem to step out of the box and the catcher wasn't making a play on anyone.

What am I missing?