<<Disclaimer: Verify this information before applying it to your situation.>>

Here's the email my husband got from Eduardo about Maseca Tortilla mix.

Corn flour does not contain gluten, that as you mention is found in
grains such as wheat.  We only produce corn flour made 100% from corn
and we do not handle gluten at all.

I contacted our Central Research and Development laboratory and they
have confirmed that corn does not contain any gluten

Please review my response and let me know if I can be of any additional
assistance