I don't know about that level, but I can think of at least one circumstance where I think far longer than would be expected over a forced move. If I've worked out the forced sequence in my head and determined that the opponent doesn't gain anything by it, but they play it anyway, I start thinking "Danger, Danger, they've seen something I haven't and I'd better re-evaluate."
Most of the time it's nothing and they just decided to play out the position earlier than I would have. But every so often I discover a flaw in the "forced" defense and have to start scrabbling for an alternative.
This is very true in Go. If you are both playing down a sequence of moves without hesitation, anticipating a payoff, one of you is wrong (kind of. It's hard to put in words.) It is always worth making double sure that it isn't you.
There have been a couple of brief discussions of this in the Open Thread, but it seems likely to generate more so here's a place for it.
The original paper in Nature about AlphaGo.
Google Asia Pacific blog, where results will be posted. DeepMind's YouTube channel, where the games are being live-streamed.
Discussion on Hacker News after AlphaGo's win of the first game.