Does having an opiate addiction make you more sensitive to pain?

generally yes: Some fairly recent studies have shown that people in Methadone maintenance programs require more post operative pain relievers and people who were not in Methadone programs. This was true even if the non-methadone patients were already taking opioid pain relievers. The neurochemistry of addiction and physical dependence are different. Addiction has a much stronger psychological component.

Possibly: I've heard a theory which suggests that opiate addicts have an increased sensitivity to pain and a disturbance of the body's natural pain control mechanism called the endorphine system. Also, taking opiates over time can actually result in making the pain worse in some cases. Often, a person starts out on low doses of opiates and then ends up months or years later on high doses but still in pain.

Opiates: Chronic use affects the endorphin system and tolerance can develop.

Apparently: Opioid dependence lowers the pain threshold over time. So less and less pain stimuli are perceived as greater and greater pain. This is a form of opioid seeking originating in the pleasure area of brain. After detox and sobriety, pain thresholds increase slowly to preaddiction levels. Perfeption of pain is one of the major reasons that opioid users have difficulty getting off them.