I have seen this a few times. The pins in the connector can be bent by install/removal of the phone. A pin can be bent and contact the metal sheath of the connector. This results in a dead short and heating results. Circuit protection and mathematical calculations notwithstanding, the plastic on the connector body has been observed to discolor and even smoke. Ignition of proximal combustibles must be evaluated on a case by case basis and should not be rejected out of hand.