This is now the second time I notice this happen: the first on November 10 of last year (which had 2 days remaining) and now today. My last time played was 6 days ago and today I logged on to see I had 9 hours left on a boost. I have not opened any lootboxes in months as I like to let them accumulate and open them all at once. My gem count has not changed and there is no purchase history on my Bnet account page.