I just noticed one can set his own Format for date-times in User Settings which could cause the regex to fail because the setting also has an effect on the displayed node creation time.

When not set, the default setting for the date format on PM currently is "%b %d, %Y at %H:%M %Z" (i.e. 'Nov 13, 2005 at 01:23 CET').
Using "%b %d, %Y at %H:%M:%S %Z" to also show the seconds would still work.

The javascript expects the variable 'timestr' to be in the format of "%b %d, %Y %H:%M:%S" or "%b %d, %Y %H:%M" (i.e. 'Nov 13, 2005 01:23') to convert the time string into unix time (aka epoch seconds).