Ignition melted

Short answer is yes. Basically the boot is there to insulate the electrode and plug from any other source of ground so that the spark makes it into the combustion chamber. When there is a crack, you have upwards of 40,000 volts going through the crack and grounding through the head. When this happens you have the heat from that spark much closer to the actual coil then it should be and it can melt it.

Go ahead and replace it and you should be good. Let me know if you have questions. Thanks