Is the spoke that pulled through the rim the one the LBS replaced? What make of rims and how many miles/kilometers are on them? By the look of that spoke and the oxidation on the eyelet, I'd say that the truing process was more than that(presumably worn out)rim could bear. Perhaps it's time for a new wheelset after all?
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"If there hadn't been women we'd still be squatting in a cave eating raw meat, because we made civilization in order to impress our girl friends. And they tolerated it and let us go ahead and play with our toys." Orson Welles