I don't know Houston specifically, but that doesn't sound too out of place for a server side java dev with 4 years of experience in the midwest.
A couple things bother me - 2 raises in 4 years. Also, dual Java and .Net work. As much as I'm a 'play in all camps' advocate, you may never get truly deep skills to justify higher pay (in future jobs) if you're doing jumping between tech.
Overall, it's not the worst pay I've ever heard of for someone with multiple years of experience in Java and .Net.
Indeed shows:
http://www.indeed.com/salary?q1=.net&l1=houston&tm=1 = $85k http://www.indeed.com/salary?q1=java&l1=houston&tm=1 = $91k
Obviously just a rough ballpark, but you're near average it seems.