security updates?

This is normal. This is why people get mad at carrier branded phones and a good reason as to why I am dumping my S8+ for the Pixel 2 when it comes out :).
 
it's almost October and my T-Mobile is still on July patch. I have bixby set to check as part of a daily quick-command. but "device is up to date" is all I get. looks like unlocked devices are getting updates faster than carrier ones now.
My US Unlocked S8+ and T-Mobile Note 8 are both on the August 1 patch.
 
it's almost October and my T-Mobile is still on July patch. I have bixby set to check as part of a daily quick-command. but "device is up to date" is all I get. looks like unlocked devices are getting updates faster than carrier ones now.

Unlocked S8 still on August patch
 
I have the Samsung S7 and can also confirm that the first August Patch causes battery drain. If you have any available update after that, install it, there is a following firmware version - August Patch with BlueBorne fixes & others, that fixes the problem. If you are still in July patch, you are probably lucky not to have the problematic version so be positive ;) Android updates are not that reliable so just stick with what you have and wait.
 
I have the Samsung S7 and can also confirm that the first August Patch causes battery drain. If you have any available update after that, install it, there is a following firmware version - August Patch with BlueBorne fixes & others, that fixes the problem. If you are still in July patch, you are probably lucky not to have the problematic version so be positive ;) Android updates are not that reliable so just stick with what you have and wait.

No issues here at all