By Lucia Mutikani WASHINGTON (Reuters) - U.S. producer prices unexpectedly fell in August amid a compression in trade services margins and mild increase in the cost of goods, suggesting that domestic firms were probably absorbing some of the tariffs on imports. The lack of strong producer price pressures, despite import duties, could also be signaling softening domestic demand against the backdrop of a struggling labor market. The Federal Reserve is expected to cut interest rates at its policy meeting ne ...