No choke, but pretty pathetic nonetheless. It's one thing not to break him, but winning just 53% of your own service points against a big server on his worst, and your best surface... Not acceptable.
It's just that Milos is catching up pretty quickly on clay. Soon he's going to be as good on it as he is on other surfaces.
It's going to be interesting to see how he does tomorrow against Almagro, whom he has beaten on hard already, earlier this year.