Spell "Light" stays visually active after it expires

Not sure if this is common or not but I've noticed after doing a long rest with the spell "Light" active on my weapon, it continues to stay lit after waking up but without the benefits. I assume the spell expires after resting? Simply reapplying the spell fixes the problem. Also noticed the light will go away after a short rest, haven't really tested it further. Is this a bug?