strftime with locale strange behaviour

In a project, i want to show dates based on user locale.
Dates are stored in a mysql table, as unix timestaps.
In order for me to show dates in specific locale I have the following code:

// in my config file:
// $setLocale is from database (examples: en_EN.UTF8 or fr_FR.UTF8 or it_IT.UTF8 etc)
setlocale(LC_ALL, $setLocale); 

//in my function file
function my_mb_ucfirst($str, $e='utf-8') 
{
    $fc = mb_strtoupper(mb_substr($str, 0, 1, $e), $e);

return $fc.mb_substr($str, 1, mb_strlen($str, $e), $e);
}

//and in any php page i want to show dates:
$dateFromDb = 1419980400; // example value from table
$date = my_mb_ucfirst(strftime("%b %d, %G", $dateFromDb));

Now the strange part:
the above date 1419980400 gives me two different results.

echo my_mb_ucfirst(strftime("%b %d, %G", 1419980400));

this gives Dec 31, 2015

echo date("M d, Y", 1419980400);

this gives Dec 31, 2014

Can anyone explains to me why this is happening?
Is there any error in the above process?

NOTE: this error/bug i verified it with three different configurations:
apache 1.3 + php 4.3
apache 2.0 + php 5.3
windows xp + xampp 1.7.4

Solution

In the german http://php.net/manual/de/function.strftime.php version there is written:

%G ... Besonderheit: entspricht die ISO Wochennummer dem vorhergehenden oder folgenden Jahr, wird dieses Jahr verwendet.

Means: it looks for the week no. and takes the previous or following year if the week falls into that.

So just take %Y instead of %G

EDIT:

The english version http://php.net/manual/en/function.strftime.php tells us:

%G The full four-digit version of %g

%g Two digit representation of the year going by ISO-8601:1988 standards (see %V)

%V ISO-8601:1988 week number of the given year, starting with the first week of the year with at least 4 weekdays, with Monday being the start of the week