Date weirdness

I think I am losing my mind. I have some time zone converting code,
and I just don't understand what I am seeing. Also my system seems to
return the wrong time after I do some date operations on unrelated
objects.

This is from a machine that is in eastern time. I want to convert to,
for example central time:


$ndate = new Date(date("Y-m-d H:i:s"));
echo $ndate->format("%Y-%m-%d %H:%M:%S");
2013-03-28 15:35:07  <- this is the correct time

$ndate->setTZbyID("EDT");
echo $ndate->format("%Y-%m-%d %H:%M:%S");
2013-03-28 15:35:07 <- still correct

$ndate->convertTZbyID("US/Central");
echo $ndate->format("%Y-%m-%d %H:%M:%S");
2013-03-28 10:35:07 <- this is wrong it should be 14:35:07

$xdate = new Date(date("Y-m-d H:i:s"));
echo $xdate->format("%Y-%m-%d %H:%M:%S");
2013-03-28 19:35:07 <- HUH? This is wrong - should be 15:35:07

What in the world is going on here?