Are HumbleBundle keys region locked?

I think some bundles had region locked keys for some games, but not many.
If I'm not wrong the sega bundles were region locked for some countries.

I think it might be based on the game, not the site you buy them from. There were some posts about some of the games from one of the recent bundles being region locked even though it doesn't explicitly state that they are. I have some of those keys still and was hoping I didn't run into that problem.

Some games are region locked and aren't marked as such. For example I had to reroll a giveway for Secret of the Magic Crystals because the winner was from Iran and couldn't activate the game. Humble Support was very nice and friendly trying to deal with this issue, but they ultimately couldn't solve it.