It sounds to me like you upset the circuit operation with static from your
finger. Try grounding yourself to something else like the power supply ground
before touching the PIC. if the floor is carpet, do not drag your feet across
it. You may also find it advantageous to have a connection from the ground side
of the PIC supply to the mains ground connection.

There may be enough static buildup to upset the PIC without you feeling a
current when you touch it - especially if the humidity is very low.