It was more of a flattening out than a significant decline, Google actually fell even more, and one month does not make a trend. That said it's worth noting that Microsoft's Bing search engine experienced a decrease in market share in the U.S. for the first time in four months in March, according to new data from Experian Hitwise.

Bing fell to 9.62 percent of the U.S. market in March, from 9.7 percent the month before, the research firm said in a news release today. The report followed three straight months of increases for the Microsoft search engine, as measured by Experian Hitwise.

Given the momentum Bing has been showing, it should be particularly interesting to see if the upcoming data from comScore Networks shows a similar trend.

Google fell from 70.95 percent in February to 69.97 percent in March, while Yahoo rose slightly, from 14.57 percent in February to 15.04 percent in March. And Ask.com appeared to be mounting a bit of a comeback, rising rising from 2.84 percent to 3.44 percent -- its fourth straight monthly increase.

As noted by eWeek's Microsoft Watch blog, the Experian Hitwise data showed Bing continuing to post gains in "vertical" search areas, such as online travel and shopping, although it's growing from a small base.