Java strange bug or what?

[VaidasB]

private void memoryDifference(String rem){
System.gc();
System.gc();
System.gc();
long memoryTotal = Runtime.getRuntime().totalMemory();
long memoryFree = Runtime.getRuntime().freeMemory();
int memoryUsed1 = (int) (memoryTotal - memoryFree);
System.out.println(String.format(rem+" used\t%,6d memory",
(memoryUsed1-memoryUsed)));
memoryUsed=memoryUsed1;
}

using this i get freeMemory larger than a totalMemory. How could it be? How can I fix it?
but not always...