Lots of leftover yeast

Oatmeal Stout
I brewed a oatmeal stout on Memorial day.
Recipe:
9# Dark malt extract
1# flaked oats
1# roasted barley
.5# chocalate malt
2 oz. Northern Brewers hops for 60 min.
Steeped grains in 150 degree water for 45 min then added and boiled 1.5# extract and hops for 50 mins in 3.5gals., then added the rest of the extract for last 10 min of boil. I topped off water to 5.5 gals.
cooled to 74 degrees and pitched 1 pkg of Nottinghams dry yeast which I rehydrated. Very active fermentation. I racked it to secondary after 10 days & it was still bubbling a little after it was in secondary. There was prabably 3 inches of yeast cake in primary, sort of clogged my spigot for a second and then flowed pretty good. After 3 days in secondary it quit bubbling and water level in airlock is equaling out. Looks like I have less than 5 gals. left to bottle. Anyway I have not had that much yeast left in primary after racking. Is this due to so much extract and fermentables or is Nottinghams yeast that active?

I think it's because Nottingham is so flocculant- more yeast settles out instead of just "floating around" in there. You'll still have plenty to carbonate your beer, though. One of the reason I like Nottingham so much is because I have such clear beers when I use it.