Of course it's possible. The question is, is it likely? Consider the sheer volume of search queries that hit Google. I find it unlikely that they could manually filter them, and I also find it unlikely that one could programmatically find those queries. Even looking for outliers (very uncommon queries) would probably yield far too many false positives.
Also, what would Google's incentive be? They are doing pretty well, as far as I can see, and they have great people. What would they gain from spying on startups, when they could just innovate inhouse, or buy the startup outright as it emerged?
Also, what would Google's incentive be? They are doing pretty well, as far as I can see, and they have great people. What would they gain from spying on startups, when they could just innovate inhouse, or buy the startup outright as it emerged?