Cruise control speed v downward slope

Hi all, new to this forum so please forgive my silly question ..

(2008 model cx9)

Is the cruise control designed to slow the car on a gradual downward slope and maintain the set speed? I noticed the car never did this until I had it serviced (25k). Shortly afterwards I was coming down the down track towards Adelaide and the vehicle seemed to 'pull up', with cruise engaged, maintaining the set speed (100km/hr), evident by a distinct feeling of reducing speed ??

Is it supposed to do this all the time? If yes, perhaps I have a possible fault in my cruise system as it has only happened once.

Again apologies for the silly question .. Cheers

Mine's the same way, it holds the speed up, down or level road. You might check the vacuum hose that feeds the cruise control module. An '08 is old enough to have hose cracks, ie vacuum leak.

Ya my p5 did that. Slowed down on long gradual downhills.