If you clear customs in Canada you should have plenty of time for lunch, even if you have to pass through security again. Since your IAH-CLT flight will depart from Terminal A you can meet at the "sports bar" previously suggested. It's not really a sports bar and it is airport food, so keep both in mind. It is outside security, however, which makes it unique for IAH. The Marriott located between Terminal B and C is a second option.