Texas A&M is having that little brother big brother mentality.
Your big brother overshadows while you're a kid. Then you go off for a few years and make your own name for yourself. Come back after those few years and you're good friends and respect each other. I think with all the hard work Texas A&M did to get out of the shadow of Texas to create their own identity in a new conference, that they just aren't ready yet to be associated with Texas at this time. Give them a few more years and I bet Texas A&M revisits having a rivalry game with them. But right now, I think they are happy being 10-2, in the Top 10, and not having to worry about Texas.