TimeStampable behaviour failure at setUpdatedAt(time())

[murraycollingwood]

I have a table where I'm using timestampable behaviour - this is in the schema.xml

  <behavior name="timestampable"></behavior>

The table contains user records and we have the fields below defined in the structure:
created_at datetime Yes NULL
updated_at datetime Yes NULL

The majority of staff uploading user records all work fine, however one particular user gets the following error. If I get this user to send me the file to upload I upload it and it works fine. Yet when they upload it they get this error.

[Wed Oct 23 22:14:53 2013] [error] [client 115.75.129.87] PHP Fatal error:  Uncaught exception 'Exception' with message 'DateTime::__construct(): Failed to parse time string (0) at position 0 (0): Unexpected character' in /home/sobs/build/classes/focus_sobs/om/BaseUser.php:1665\n
Stack trace:\n#0 /home/sobs/build/classes/focus_sobs/om/BaseUser.php(1665): DateTime->__construct('0')\n
#1 /home/sobs/build/classes/focus_sobs/om/BaseUser.php(1954): BaseUser->setUpdatedAt(1382530493)\n
#2 /home/sobs/build/classes/focus_sobs/UserPeer.php(676): BaseUser->save()\n
#3 /home/sobs/build/import3-content.php(124): UserPeer::import(Array, true, 861, false, false)\n
#4 /home/sobs/build/topline.php(302): include('/home/sobs/buil...')\n
#5 /home/sobs/build/pt/import3.php(9): include('/home/sobs/buil...')\n
#6 {main}\n  thrown in /home/sobs/build/classes/focus_sobs/om/BaseUser.php on line 1665, referer: http://sobs.com.au/pt/import2.php

This staff member is in Vietnam yet we are both on the same server in Australia. The php.ini looks like:
[Date]
; Defines the default timezone used by the date functions
; http://php.net/date.timezone
date.timezone = Australia/Brisbane

Looking at the code in BaseUser.php
Line 1954: $this->setUpdatedAt(time());

And the function setUpdateAt()
public function setUpdatedAt($v)
{
$dt = PropelDateTime::newInstance($v, null, 'DateTime');
if ($this->updated_at !== null || $dt !== null) {
Line 1665 $currentDateAsString = ($this->updated_at !== null && $tmpDt = new DateTime($this->updated_at)) ? $tmpDt->format('Y-m-d H:i:s') : null;
$newDateAsString = $dt ? $dt->format('Y-m-d H:i:s') : null;
if ($currentDateAsString !== $newDateAsString) {
$this->updated_at = $newDateAsString;
$this->modifiedColumns[] = UserPeer::UPDATED_AT;
}
} // if either are not null
return $this;
} // setUpdatedAt()

A value is being passed in here, however the $this->updated_at does not seem to have been populated, and neither is it null, but a '0', which causes the error in the DateTime constructor.

Perhaps we should test for 0 or null and do the same process.