The S&P Case-Shiller Home Prices Indices rose 13.3 percent in September compared with this time last year, the highest year over year price increase since February 2006.

Prices were up 3.2 percent in the third quarter according to the index. Thirteen of the 20 cities tracked by the index posted higher year-over-year prices in September, including Boston, where prices were up 0.5 percent compared to August and 7.5 percent year over year, according to the index.

"The second and third quarters of 2013 were very good for home prices," David M. Blitzer, chairman of the index committee at S&P Dow Jones Indices, said in a statement. But Blitzer said the high numbers were not a cause for concern. "The strong price gains in the West are sparking questions and concerns about the possibility of another bubble. However, the talk is focused on the 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."

Other commenters questioned whether the Case-Shiller numbers were an accurate reflection of the true state of the market.

"Honestly, I’m just not sure what to make of these numbers. A slew of recent reports, including [our own], all indicate a slowing market with formerly stratospheric home price appreciation rates beginning to fall back to earth," Zillow Chief Economist Stan Humphries said in a statement. "Zillow’s own data, which excludes REO re-sales, shows the same markets that dominate the Case-Shiller indices – particularly some of the California markets – to be cooling. This suggests that Case-Shiller’s inclusion of REO re-sales is heavily skewing overall appreciation in these markets. If people are really focused on REO appreciation, they should take a closer look at Case-Shiller. But I think most people are more concerned about the broader market, and I’m not sure Case-Shiller is doing a good job of characterizing that market."