To reproduce, create the following test case:

[Test]
public void TestGetTimeAfter() {

    CronExpression cronExpression = new CronExpression("0/10 * * * * ?");
    DateTime afterTime = new DateTime(2007, 08, 02, 8, 59, 51);

}

This fails on line 1383. It is trying to create a date with the minutes set to 60 (seconds have been rolled to 0). Need to check and increment the hour accordingly....

if(min == 60) {
   int hour = d.hour + 1;
}