I really do think a "thank you" as if you noticed this, and are -sure-* they didn't make ANY mistake, but wanted you to have a little extra money as an under the table bonus, would be a better way to walk into that conversation, and it would also serve notice that you are one of those folks that actually reads, notices, understands and can do the math of what their paycheck should say, and that will serve to your managers not to screw or make a mistake with your pay in the other direction, where you would be missing some of your expected pay.
What if they paid you the time someone else was supposed to be paid for, and that person is short of their pay, how fair is it to that person. it seems pretty likely to me that the company knows how many hours were to be paid for in total.
sarcasm on
*Surely the management would NEVER make ANY mistake with an employees pay.
sarcasm off