WASHINGTON (AP) -- The number of people seeking unemployment benefits rose last week to the highest level since late February. But the increase likely reflected temporary auto plant shutdowns rather than any underlying labor market weakness. The Labor Department says that people filing applications for unemployment benefits rose by 15,000 to 297,000. That is the highest weekly total since 327,000 applications were filed in the week of Feb. 28. One of the states posting a large jump was Michigan, home to many U.S. auto plants, which typically see plant shutdowns in the summer to retool for a new model year. Even with the recent increases, benefit applications, a proxy for layoffs, remain at low levels that reflect an improving labor market.