I guess mowing the grass in the last week of October is one of the benefit's of living in a hot a-- place like south Texas, i guess.
Thatch is a by-product of properly fertilized and watered warm season grass and you don't want a thatch layer thicker than 1/2 inch but don't let it worry you. Get a soil probe so you can see exactly what's going on.
You can get one of those round type profiler's for $25 anywhere or you can go wild and spend $200 on a flat profiler.
A spring time aeration might be too aggressive. Zoysia need's to be 100% green and the soil need's to be warm before you go punching hole's in it.
I can see where your neighbors's are envious of your grass, keep it up.