Yes mine appears to be inside security as well; it says the following on my confirmation:

Enrollment Center: Houston Term E - BOARDING PASS REQUIRED TO ENT
Directions: Houston Intercontinental Airport, Terminal E inside sterile corridor by Ruby’s Restaurant

I'm not sure exactly where that is inside security (anyone know, exactly?), but hopefully it will be obvious if I roam around near Ruby's Restaurant.

Only reason I chose it was that there appears to be a lot of availability upcoming, perhaps because it is brand new.