One of the best tips, going forward, that I could give you is to fix your W-4s and withhold $10 on Fed and $5 on State. Or more, but back in the early 90s my stepdad made sure that I did that when I started working.
Can you take your W2 and fill the numbers into a free online tax provider? The IRS even has links. That'll put your mind at ease.
To add. You've gotta figure he was fully blue blooded, a union Construction guy who lived through the last major tax reform in the 80s.
To add more. I survived this one. Adjusted my W4s under the guise of plausible deniability. I had more withheld and didn't notice much difference in "more in my paycheck"... We have an employee page at work and I played with my settings to make it so that I saw no changes. I played with single and head of household and withholding numbers. Never trust the government when they say more in your wallet...