Secondary storage

I made an imperial stout and I then racked it into a secondary to age for about 2 months and after about 3 days there is a noticeable sediment layer on the bottom. I am confused because I have read that if you leave your fermented wort on the yeast layer for to long it will end up not good so that is why you put it in the secondary, now I am wondering if I should rack it again because of the aformentioned sediment. I knew there would be some sediment but not that much.

Let it age for a few weeks. I would let it go for a month before packaging.

Don't sweat that sediment if you waited until the primary fermentation was done to rack...I've left beers in the secondary for up to 3 months with no ill effects and know that others have gone ~1 year. You're going to have that sediment...some of it may be flocc'ing yeast, some of it may be break, but it won't hurt anything.