There were changes that were made to fine-tune the system so that would explain why you were temporarily above the threshold and then below again. Other than keeping a balance above $50 you can also play Hi-Lo, jackpots, or buy lottery tickets as it is a combination of all those things.
Ok, I will continue doing it.
By the way excuse me if I sound ignorant but this will be permanent for my account?
PD: (To avoid an answer thanking you) Thanks for the quick reply.