UIBarButtonItem textures offset when iPhone only app is run on iPad - objective-c

Question

In the main view of my app, I instantiate 3 UIBarButtonItem(2 actual buttons and 1 flexible spacer) with custom images (created using [UIImage imageNamed:]), then set them as the items of a UIToolBar. Here's the code:
-(void)viewDidLoad{
[super viewDidLoad];
UIToolbar *menuBar = [UIToolbar new];
menuBar.barStyle = UIBarStyleDefault;
CGRect viewBounds = [UIScreen mainScreen].bounds;
//menuBar is rotated to be viewed vertically along the right side of the device in portrait orientation, the app does not support device rotation
menuBar.transform = CGAffineTransformRotate(menuBar.transform, M_PI * 0.5f);
[menuBar setFrame:CGRectMake(viewBounds.size.width - menuBarHeight, 5, menuBarHeight, viewBounds.size.height)];
[self.view addSubview:menuBar];
[menuBar release];
UIBarButtonItem
*peekButton = [[UIBarButtonItem alloc]
initWithImage:[UIImage imageNamed:#"peekIcon.png"]
style:UIBarButtonItemStyleDone
target:self
action:#selector(peek:)],
*pauseButton = [[UIBarButtonItem alloc]
initWithImage:[UIImage imageNamed:#"pauseIcon.png"]
style:UIBarButtonItemStyleDone
target:self
action:#selector(pauseGame:)],
*flexSpace = [[UIBarButtonItem alloc]
initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace
target:nil
action:nil];
menuBar.items = #[flexSpace, pauseButton, peekButton];
[flexSpace release];
[pauseButton release];
[peekButton release];
}
When run on a iPod touch running iOS 5.1, the toolBar and buttons appear as expected, like so:
but when run on an iPad(iOS 4.3), the textures look like this:
I can not seem to discern the cause, however, I believe it may be an OS, or device specific bug, as I keep encountering similarly obscure graphics issues where UI elements are drawn with total disregard for the underlaying object's data. Unfortunately I can't find any relevant docs (Apple or other wise) to shed some light on this issue.
Any input is greatly appreciated, thanks.

Answer 1

The issue seems to arise from calling UINavigationController's method
-(void)pushViewController:(UIViewController*)viewController animated:(BOOL)animated;
As screen transitions were not originally intended to be animated, the animated argument was NO. Changing the value to YES seems to be the solution.
This also seems to have solved some other graphics issues I was experiencing.