Maybe.  Why did the Mexican Citizen not qualify before getting married?

Some possible reasons:

1. She was not a US Resident Alien:  Filing a Joint tax return and making the election to be taxed as a full-year Resident would not qualify her.
2. She did not have a Social Security Number.  Just getting married won't fix that, she would need a Social Security Number.
3. She did not live in the US for at least 1/2 of the year.  Again, just getting married won't fix that, she would need to live in the US for at least 1/2 of the year.