It is called TALL FESCUE for a reason!

I realize how impressive the lawns look cut at 1.5 to 2 inches right now. However, we are trying to manage TALL fescue. Right now, fescue is still producing root growth and top growth with current soil temps. Once we hit late May, the root growth slows dramatically due to rising soil temps. Two bad things happen with low mowing height. First, Root depth/mass is proportional to height of cut. If you mow higher now, you will have more root production to get you through the shake and bake of summer. 
Lastly, lower height allows more sunlight to reach soil, breaking down pre-emergents quicker and promoting summer weed invasions.
FYI – Just because your mower says 3 inches on its adjustment, doesn’t make it so. Please take a ruler out right after mowing and make sure you have 3 inches of grass height remaining.
Last thing: I know you invest lots of $ into your lawn, so I understand if you want it to look mind blowing through April by mowing low. Please make sure to raise your height no later than May 1st to 3 inches. It will make us all happier in heat of summer. Thanks!