You might hear people make reference to 'lees', 'leesy-ness', 'on lees', or 'autolysis/autolytic' flavours in wine. 

Lees is the name we give to yeast posthumously (post-yeast-ously?). They are the skeletons (or cells, if you're committed to being strictly correct) of yeast that have finished turning sugar into alcohol - their fermentation period - and died. 

When the yeast die, they fall to the bottom of the fermentation vessel. The bottom of a fermentation vessel is essentially a yeast graveyard, and the wine sits on top of it. It's a wonder more wine isn't haunted, actually. 

The winemaking choices are to take the wine off the lees, leave it on the lees, or to stir the lees back into the wine (French: batonnage). Where wine is left on lees, or lees are stirred back into the wine, then you'll get toasty, brioche, biscuity, nutty (specifically almonds), yeasty depth in the wine - aiding complexity (which is a marker of quality), as well as added texture, weight and a broadness on the palate.  

Importantly, this is by no means an uncommon occurrence, so if you think you detect it, you probably do. Notably, you'll likely (but not exclusively) see evidence of lees in Champagne, Chardonnay, Loire Valley Chenin Blanc and Muscadet - look for the Sur Lie (literally 'On Lees') designation on the bottle.