Bottom 8th, R1, starts at 2:24:50 on MLB TV if you want to look at it. From the 2B view it looks like a jab step without a throw to 1B which would be a balk. U2 starts to do something but PU comes out from behind the plate and motions something to U2. U1 and U3 are not in view but they probably had the best view on whether it was a jab step or a step back. Apparently they had nothing. But, it's MLB. See if this link works:
http://mlb.mlb.com/media/player/mp_t...hnmlb-slnmlb-1