It has only happened a few times and not sure if i should worry or not.

To explain as best i can

Decending a hill at 35-40 in third, hit brakes to slow car to 15ish, drop into second gear. At this point i am off the brake and the clutch pedal. I then turn right and it sounds like a whine from the rear passenger side?

It has happened a few times before just curious to know what it might be, it tends to be happen when turning and is usually at quite a low speed.

It it helps the car is a 1.9TDi GLX, and it is on 135k miles, the rear brakes are drums.

Was wondering if something was sticking, or he bearing were on the way out.

When it next happens, tap the brakes and see if the noise goes away. Gently pull on the handbrake and see if the noise goes away.

It sounds like the drums are binding. They may be binding at higher speeds but are not making the noise.

You need to check the shoes AND drums for wear. Maybe they just need a good clean.

Sounds like a bearing to me.