Other search engines have made search string information publicly available. Similarly, there is no reason Google could not expand tools like Google Trends or Google Zeitgeist to provide the public with details about your patent search string and, in turn, your invention. A larger, more immediate problem is how a judge might rule as to whether a Google Patent Search constitutes a patent invalidating disclosure under 35 USC Section 102.
A court is not likely to rule that a simple search that never left Google constitutes an enabling disclosure sufficient to trigger 35 USC Section 102 invalidity. A court might have a different opinion, however, if you are deposed on the matter. Admitting that you conducted a patent search on Google, but have no record of what terms you plugged into Google or whether Google kept that information confidential, might make for a rather uncomfortable day in court.
Worse, in the event Google does make Google Patent Search information public between the time you conduct your search and file your patent application, you could have significant problems with the validity of your patent both in the United States and overseas.