The Wall Street Journal seems to think so. Although they are not 100% sure:
Sen. Obama already has begun pivoting toward the general election. Soon, he will be in position to unleash a barrage of attack ads aimed at defining Sen. McCain, though it’s unclear when or whether the campaign will do so. With vastly more money, Sen. Obama could flood the airwaves as voters are forming impressions.
A preview erupted yesterday when, in an interview on cable news, Sen. Obama suggested Sen. McCain was "losing his bearings."
Not exactly breaking news. But interesting food for thought. Somewhere in maverick-land people are probably starting to get a bit concerned.