Text in label getting distorted when setting shadow on underlying view?

Im currently using the code below to render the view for my sectioned tableView

- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section
{
    UIView *headerView = [[[UIView alloc] initWithFrame:CGRectMake(0, 0, tableView.bounds.size.width, 30)] autorelease]; 

    headerView.backgroundColor = [UIColor colorWithRed:30/255 green:30/255 blue:30/255 alpha:1.0];
    headerView.layer.masksToBounds = NO;
    headerView.layer.shadowOffset = CGSizeMake(0, 0);
    headerView.layer.shadowRadius = 3;
    headerView.layer.shadowOpacity = 0.5;
    headerView.layer.shouldRasterize = YES;

    UIBezierPath *path = [UIBezierPath bezierPathWithRect:CGRectMake(0, headerView.frame.size.height, headerView.frame.size.width, 3)];
    headerView.layer.shadowPath = path.CGPath;

    UILabel *label = [[[UILabel alloc] initWithFrame:CGRectMake(12, 7, tableView.bounds.size.width - 10, 20)] autorelease];
    label.font = [UIFont boldSystemFontOfSize:16];
    label.text = header;
    label.textColor = [UIColor whiteColor];
    label.shadowColor = [UIColor bla开发者_StackOverflow中文版ckColor];
    label.shadowOffset = CGSizeMake(0.0f, 1.0f);
    label.backgroundColor = [UIColor colorWithRed:30/255 green:30/255 blue:30/255 alpha:1.0];
    [headerView addSubview:label];

    return headerView;
}

For some reason though the text is being mangled a bit and a little distorted? I have narrowed it down to the effects i am putting on the layer although im not sure why its doing it?

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I see you are setting shouldRasterize to YES. Does setting the rasterization scale help? This would only be needed if you are using an iPhone 4.

 [[headerView layer] setRasterizationScale:[[UIScreen mainScreen] scale]];