friction brake burp/grunt

I don't think this has anything to do with brake "groan" others have experienced.
Since new my v has made burping/sucking noises sometimes when the friction brakes bring the car to a stop between 5-0km/h. Sometimes I can get the brakes to make the noise by pumping the brakes with the vehicle in park.
currently 43000km on the odomoter so my v has had its first brake service already. I never thought to mention the issue to a service advisor as i thought it was normal sounds from ABS braking but now i'm not so sure. I'm familiar with the ABS sounds when stopping on an ice covered road, the clicking/pedal pulsing, so its not that.
After major brake service the noise went away for awhile but i've since noticed it seems to be related more to colder weather. Only heard when outside temperatures are below 20*c. Another factor is weight in the vehicle. Carrying 3 other adults in the car the noise occurs at almost every stop.
Anyone else experience this?