US home prices have soared to new heights and they keep on climbing, and some researchers and economists say they have seen signs of a housing bubble brewing.

Home prices are rising faster than market forces would indicate they should and are becoming “unhinged from fundamentals,” according to a new blog post written by researchers and economists at the Federal Reserve Bank of Dallas.

Until recently, the possibility of a bubble wasn’t widely supported. But after looking at housing markets across the US, the Fed researchers said new evidence is emerging.