From what I've been reading autolysis is a potential factor for big breweries. Imagine you have a few hundred gallons of beer sitting on top of yeast that's fallen out of suspension and is being squeezed down into the conical portion of a fermenter, crushed by the massive weight of all the beer above. That's why they dump the yeast or transfer the beer to a brite tank at the appropriate time (correct me if I'm wrong, I'm not an authority on the operations of big breweries). For 5 gallons of beer sitting on the yeast after it flocculates, you shouldn't have any concerns. I'm a new brewer and I personally haven't left any beer in the primary longer than 4 weeks but I've been reading plenty of reports of people leaving it for months.