Yes, if you entered everything correctly, exactly as it appears on the form,. and you answered all the followup questions correctly, then the amount owed is right.
When you enter income, especially this much income, it doesn't just add an additional tax to your return. The income changes your Adjusted Gross Income, and with that change, many others can occur. Itemized deductions can become limited, and so can credits. The tax rate on this income may be much higher than the rate at which the rax was withheld by the issuer and the additional income may even cause a penalty for not paying enough in estimated tax during the year. There are just all sorts of things that change with each entry you make.
If you took an early distribution, there's also a 10% early distribution penalty.
