UIImageView isAnimating break in 4.0 SDK?

The following code used to work with iOS 3.x. Now with 4.x this will not work. In other words, I can run two identical applications on one device, one of which is created against version perx 4.x, and the other with 4.3, and in the second - isAnimating does not change the value if the screen is not listening, or change the orientation.

Here is the relevant code. I started with a view-based template in Xcode.

- (void)viewDidLoad {
    [super viewDidLoad];
    iv.animationImages = [NSArray arrayWithObjects:
                                      [UIImage imageNamed:@"timer00.png"],
                                      [UIImage imageNamed:@"timer01.png"],
                                      [UIImage imageNamed:@"timer02.png"],
                                      [UIImage imageNamed:@"timer03.png"],
                                      [UIImage imageNamed:@"timer04.png"],
                                      [UIImage imageNamed:@"timer05.png"],
                                      [UIImage imageNamed:@"timer06.png"],
                                      [UIImage imageNamed:@"timer07.png"],
                                      [UIImage imageNamed:@"timer08.png"],
                                      [UIImage imageNamed:@"timer09.png"],
                                      [UIImage imageNamed:@"timer10.png"],
                                      [UIImage imageNamed:@"timer11.png"],
                                      [UIImage imageNamed:@"timer12.png"],
                                      [UIImage imageNamed:@"timer13.png"],
                                      [UIImage imageNamed:@"timer14.png"],
                                      [UIImage imageNamed:@"timer15.png"],
                                      [UIImage imageNamed:@"timer16.png"],
                                      [UIImage imageNamed:@"timer17.png"],
                                      [UIImage imageNamed:@"timer18.png"],
                                      [UIImage imageNamed:@"timer19.png"],
                                      [UIImage imageNamed:@"timer20.png"],
                                      [UIImage imageNamed:@"timer21.png"],
                                      [UIImage imageNamed:@"timer22.png"],
                                      [UIImage imageNamed:@"timer23.png"],
                                      [UIImage imageNamed:@"timer24.png"],
                                      [UIImage imageNamed:@"timer25.png"],
                                      [UIImage imageNamed:@"timer26.png"],
                                      [UIImage imageNamed:@"timer27.png"],
                                      [UIImage imageNamed:@"timer28.png"],
                                      [UIImage imageNamed:@"timer29.png"],
                                      [UIImage imageNamed:@"timer30.png"],
                                      [UIImage imageNamed:@"timer31.png"],
                                      [UIImage imageNamed:@"timer32.png"],
                                      [UIImage imageNamed:@"timer33.png"],
                                      [UIImage imageNamed:@"timer34.png"],
                                      [UIImage imageNamed:@"timer35.png"],
                                    [UIImage imageNamed:@"timer36.png"],                                      nil];
    iv.animationDuration = 5.0;
    iv.animationRepeatCount = 1;
    [iv startAnimating];
    timer = [NSTimer scheduledTimerWithTimeInterval:0.5 
                                             target:self 
                                           selector:@selector(periodicallyUpdateView) 
                                           userInfo:nil 
                                            repeats:YES];
}

- (void)periodicallyUpdateView {
    if ([iv isAnimating]) {
        NSLog(@"it is animating");
    }
    else {
        NSLog(@"it is NOT animating");
    }
}

Does anyone else see this?