Either that, or try changing the phone. There's probably dust underneath. If digitizer is expensive, try pulling it out, give it a personal service like dusting and vacuuming(make sure you dont vacuum some of the easily loose part out.
I did that with a small portable vacuum, works like a charm.
Name: Nexus 4 Mako
ROM: BrainMaster JWR
Kernel & Tweaks: Franco/Trinity
Devices I once had(Or still have):
LG Nexus 4(present), Samsung Nexus S(present), LG Optimus 4X HD P880(sold), HTC Sensation XE Pyramid(sold), Samsung Galaxy Wonder i8150(spare)
Devices I have minor experience about:
Samsung Galaxy Y, Samsung Galaxy i9100, Samsung Galaxy i9100G, Samsung Galaxy SIII Mini i8190N, HP iPaQ500(retired and yes its an antique)