Is requiring a certain order for #includes in c++ a sign of bad library/header design?

// A.cpp
#include "A.h"
#include "boost/shared_ptr.hpp"
#include <vector>

class A {
// ...
};

//a.h
#ifndef _A_H_
#define _A_H_

//... code ...

#endif
// -----------------
//b.h
#ifndef _B_H_
#define _B_H_
#include a.h

//... code ...

#endif
// -----------------
//main.cpp Try 1
#include "b.h" //<- okay!  b includes a, then does b
// -----------------
//main.cpp Try 2
#include "a.h" //<- includes a
#include "b.h" //<- okay!  b includes a, but skips redefining it, then does b
// -----------------
//main.cpp Try 3
#include "b.h" //<- b includes a, then does b
#include "a.h" //<- okay!  a skips redefining itself!
// -----------------
//main.cpp Try 4
#include "a.h" //<- fail!  b is not included anywhere =(

// A.h
#pragma once
// or the #ifndef trick
#include "B.h"

// A.cpp
#include "A.h"

// A.h
#pragma once
// or the #ifndef trick
//#include "B.h"

// A.cpp
#include "B.h"
#include "A.h"

class B; // forward declaration

class A
{
    void doStuff(const B& b);
};

#include <A.h>
#include <B.h>

int main()
{
    A a;
    B b;
    a.doStuff(b);
}