I suspect there's a fair chance safelife may well be crew. Certainly what he/she describes (door areas on some types being arctic cold) is a common observation and may well be one explanation for what you experienced.
However aside from the cabin crew winding the zone temperature up ( which does sometimes happen) the air conditioning systems themselves on some types aren't really that sophisticated and you can get considerable differences within a zone.
On my last trip it was so hot I even had to strip off my Virgin pyjamas and sleep only in my underpants because the cabin was so hot. I was not alone in my observation from asking around. (I did loosely place the blanket across me to limit the visual distress to my fellow passengers!).
In that particular case I wonder if there had been a partial system failure - there's always the chance that due to some defect a particular zone's temperature may become very difficult or impossible to control with any finesse, e.g. if it's own "mixer valve(s)" fail. On many of the Boeing's there's often the ability to override the whole system from the Flight deck and run everything in a degraded mode but it's bit of black art and very difficult if not impossible to get every zone running at an ideal temperature .