I actually don't even see pbarnette's posts unless someone quotes them. However in this case, he is correct. Just because your bonus check had a larger withholding than normal, that doesn't mean you pay more taxes on it in the end.

The way withholding works is that the withholding tables assume your paychecks will be the same all year as your current check. So if you get paid weekly and your bonus check is $10K, the withholding tables are set up to assume you make $520K a year ($10K x 52) and they withhold accordingly. It all gets balanced out at year-end when you file your income tax return though.