adwhirl error: AdWhirlAdapterCustom webBrowserClosed

Question

-[AdWhirlAdapterCustom webBrowserClosed:]: message sent to deallocated instance 0x7408a90

This is the full error message I get. My setup is the following:

- (void) viewDidLoad {  
    self.adView = [AdWhirlView requestAdWhirlViewWithDelegate:self];   
    self.adView.autoresizingMask = UIViewAutoresizingFlexibleWidth;  
    [self.view addSubview:self.adView];  
...
}

//view states  
- (void)viewWillAppear:(BOOL)animated {    
    self.adView.delegate = self;  
    [self.view addSubview:self.adView];  
}  

-(void)viewDidDisappear:(BOOL)animated {  
    [self.adView removeFromSuperview];  
    self.adView.delegate = nil;    
}

I am getting an error message after the following steps:

1. display an AdWhirl popup
2. receive a memory warning
3. the user dismisses the ad.

The viewDidLoad recreates the rest of the view, but AdWhirl generates this error.

Thanks for any insight.