RIS finally carbonated after 6 weeks

Patience Grasshopper, Patience. I tasted my recent Russian Imperial Stout, a 9.8% ABV 90 IBU Old Rasputin clone, after 10 days, 3 weeks and 4 weeks and there was no carbonation, perhaps a slight fizz on the tongue. So I decided to grow up some of the yeast I had stocked and innoculate it at about a million per ml along with glucose at a rate of 2 oz/4 gal into the uncapped bottles, then recap. I lined up a half dozen bottles, got my yeast and glucose ready, and popped the first cap. Pfffft! carbonation. I poured the bottle into a glass to get a 2 finger head and tasted it for a satisfying slurp of warm, but carbonated beer. I had already known the beer tasted great, just no carbonation. So, I have 4 gallons of a really nice RIS along with the 4.5 gallons of APA I bottled today. I guess the relatively long fermentation (about 4 weeks) and the relatively high alcohol just stressed the yeast and it took a very long time to get going again. Unless, the carbonation is uneven due to poor mixing of the glucose. I guess I'll have to wait and see.