I also got the first email but I didn't get the second one about the costs. I also was only a couple hundred points away so I managed to book a quick overnight business trip this week which should cover it. Apparently I've booked a lot of super cheap flights this year hence why it's taken me so long to re-qualify for 2019. I've flown way more than 30 times. So keep that in mind if you're planning to qualify next year. A Mint flight or two may not be a bad idea.
Re WN: I also did the Challenge when they ran it over the Summer so I'm now A-List through Summer 2019. I like it because I fly a lot of 6am flights out of LGA so I don't need to worry about boarding position now and so far the A-List seems to be prioritized over EarlyBirds.