Home prices in the nation's largest metro regions posted strong gains in September, although the pace of those increases slowed in most cities, according to a leading gauge. The Standard & Poor's/Case-Shiller index of 20 U.S. cities, released Tuesday, rose 0.7% from a month earlier and 13.3% from September of last year. Western cities saw the largest annual price gains. Prices in Las Vegas rose 29.1%; San Francisco 25.7%; Los Angeles 21.8%; and San Diego 20.9%. "The strong price gains in the West are sparking questions and concerns about the possibility of another bubble," David M. Blitzer, chairman of the index committee at S&P Dow Jones Indices, said in a statement. However the talk is focused on fear of a bubble, not a rush to join the party and buy. Moreover, other data suggest a market beginning to shift to slower growth rather than one about to accelerate. On Monday, the National Assn. of Realtors said signed contracts for previously owned homes fell to a 10-month low in October. And the Case-Shiller index showed that 19 cities saw month-over-month home price increases decelerate compared to August. The index, created by economists Karl E. Case and Robert J. Shiller, is one of the most widely followed gauges of home values. The housing index compares the latest sales of detached houses with previous sales and accounts for factors such as remodeling that might affect a house's price over time.