Your wife's Notice of Assessment should give details if her income changed from the tax return you filed using TurboTax. If she missed reporting a tax slip (T4E - Employment Insurance is common, or another T4), CRA will add this income to her tax return and issue the assessment stating they added something and where it was from.

If her income changed, your Spousal Amount would change, and result in a lower refund.  

I thought about that but her return did not change from what was submitted, only mine. I just can't understand how TurboTax came up with a number $1, 800 different than cra.

You might be able to find discrepancies by comparing the line numbers from your NOA and their corresponding values on the PDF copy of your tax return that you saved in TurboTax. It's hard to tell from this forum where the discrepancy occurred. You might want to give CRA a call and inquire about this. 1-800-959-8281