Can I update iOS 6 on my unlocked iPhone 4?

I had my iPhone 4 unlocked at a Tmobile store, they snipped my Tmobile sim card and inserted it. I'm guessing they didn't jailbreak it either. So if I update it to iOS 6, will my phone be locked again?

There's no point

It could be, thats y you should WIRELESSLY PERMANENTLY FACTORY UNLOCK any AT&T iPhone at http://iswapple.com
it works for any iphone 3gs 4 4s 5 and any firmware. Plus once you do it you can also update when ever you want because its a factory unlock… Cheapest wireless unlock it was like for 20 bucks