Is this a bug in G++ STL ?

[Jerry]

I met a strange problem while trying  string class in Standard
Template Library .

//////////////////////////////////////////////////////
#include <stdio.h>
#include <string>
using namespace std ;

main()
{
  string ss = "hello ";
  {
    string s1 = ss+ "my Friend";
    printf("%s\n", s1.data());
  }
  {
    string s2 = ss+ "my God";
    printf("%s\n", s2.data());
  }
}
//////////////////////////////////////////////////////

When I compile these code using GCC under Linux and FreeBSD, I got a
result like this:

hello my Friend
hello my Godend

If I compile the code using MSVC, I got this:
hello my Friend
hello my God

Is there a bug in GCC compiler or I was just doing wrong?