If you were working (i.e. not a lunch), you must be paid for the time spent working. You could file a complaint with the department of labor for this violation of the wage and hour laws, but it would only be worthwhile doing so if this regularly, commonly, repeatedly, etc. occurs--not if it only happened once or twice, since all you'd get is that extra one or two hours of pay, after having filed a legal complaint vs. your employer (and having spent your time doing so).