Welcome to the site :o)

Thanks for the GA.

I want to advice that you set a minimum level for your future GAs, i recommend min. level 2, because each one that gave one, not free, game is, at least, level 1.
Easy solution to hold the worst rulesbreakers, win resellers, autojoiner user and bots outside (40% of the level 0 accounts have infractions for unactivated or multiple wins + the ammount of used autojoiners are much more as in higher levels).
And besides that it lowers the cases of problems with your winners.

You can check accounts/your winners with:
http://www.sgtools.info/activation
http://www.sgtools.info/multiple-wins

If someone have red marks there request a reroll and put the link(s) into the support ticket.

https://www.steamgifts.com/stats/community/users
Scroll down to the bottom and look at the "per level" info and you see 970k are level 0, only around 165k have a level, 113k of them are level 1. So around 15% of the members from sg gave something and only 4% gave more as 5 games.

Have a nice day