Though Sprint Nextel S posted a bigger drop in wireless postpaid customers than we’d expected, there was a lot to like in the first-quarter results. Sprint lost a little momentum in the fight to win new postpaid customers, as a number of factors pressured it during the quarter, notably the iPhone launch at Verizon Wireless VZ VOD . A price increase Sprint put in place during the quarter also may have pushed some new customers away, but the move didn’t hinder improvement in customer loyalty—postpaid customer churn hit....