I was having the same issue.
I found out that it was caused by the way I initially sized the view of the parent of the modal viewcontroller.
I was using [UIScreen mainScreen].bounds
This is now what is working for me:
// loadView method of the parent of the modal view controller
- (void)loadView {
CGRect frame = [UIScreen mainScreen].applicationFrame;
self.view = [[[UIView alloc] initWithFrame:frame] autorelease];
[self.view setAutoresizingMask:UIViewAutoresizingFlexibleHeight|UIViewAutoresizingFlexibleWidth];
// Below is the actual code with the content of the view
[...]
}