Problem detecting if UITableView has scrolled to the bottom

I'm using the following code to detect if I've reached the bottom of a UITableView

- (void)scrollViewDidScroll:(UIScrollView *)scrollView{ 
    if(self.tableView.contentOffset.y >= (self.tableView.contentSize.height - self.tableView.bounds.size.height)) {
        NSLog(@"bottom!");
        NSLog(@"%@", [self getLastMessageID]);
        [self getMoreStuff:[self getLastMessageID]];
    }

}

This works fine, but the only problem is when the user is pulling the tableview down (like pull to refresh) the code fires. How can I handle this?