std.typecons scoped question

[Martin]

What is the reason behind the wasted memory when using the scoped 
template from std.typecons? For example

class A { }

class B
{

	typeof(scoped!A()) a;
	
	this()
	{
		a = scoped!A();
	}

}

void main(string[] args)
{
	writeln("Size of class A: ", __traits(classInstanceSize, A));
	writeln("Size of class B: ", __traits(classInstanceSize, B));
}

Prints the following:
"Size of class A: 8"
"Size of class B: 24"

An extra 16 bytes for alignment? Is there no options like 
align(1) to pack the memory of the class A instance inside class 
B?