Calendar.WEEK_OF_MONTH gives different results on two different devices

I have two devices HTC with android 2.3.5 and Samsung with 2.3.6 now the problem i am facing is i need the date's week of month.

So i've written this code and installed on both the phones. and set the system date as

27th Jan 2013

  Calendar calendar = Calendar.getInstance();
  int weekOfMonth =  calendar.get(Calendar.WEEK_OF_MONTH);
  Log.i(TAG,"weekOfMonth = "+weekOfMonth);

now on HTC the output is

 weekOfMonth = 5

while on samsung running the same code produces

 weekOfMonth = 4

this really is screwing my logic n calculations ahead.

am i doing something wrong ?