Peppery flavor in stout yeast

I brewed an imperial stout with coffee, bourbon and oak. It tastes wonderful but the little bit of yeast sediment at the end of the bottle, when some of it is poured with the end of the bottle it has a spicy/peppery taste (like chiles). I'm just wondering what causes that. I see some places as listed as an off flavor but it's not in the beer itself, only in the yeast sediment. I used Wyeast 1084 Irish Ale yeast if it matters. I didn't see pepper/spicy listed as a phenol or off taste for that yeast from the manufacturer.

 

everywhere i've read points to the coffee

 

Yeah that's what i've read as well, but it's only in the sediment of the bottle and not in the beer itself. I guess the peppery note from the coffee is being absorbed by the sediment only? Just odd.

 

I also remember talking with some pros about the green bell pepper (vegetable not spice) you sometimes get in DIPA's and Imperial Stouts and they say dark malts and hops have this effect sometimes. I don't think it's the yeast.