Flat battery screen not appearing on my iphone 6 plus

Hi so just today i decided to drain out my iphone 6 plus' battery completely. Before charging, i tried turning it on and realised my phone does not show the flat battery screen with the lightning cable. Instead, the dark screen just lighted up. I dont even know if this is a problem but I just want to know if this is normal because I usually see the flat battery screen with the lightning cable after draining my battery of my iphone 5 that i used in the past.