Usually door and bonnet Iswara more prone to rust. Maybe your park under sun dry up, Wira under roof got water.....lolGot rust on both doors. All aligned to one straight line. Must be the glue thing inside like the roof?
The Iswara in my house is at the same age as my Wira but it seems to have less rust problem than my car. My car is usually parked inside under the roof while Iswara is only parked outdoors under the sun for years.