It's not a Python bug: your regex is invalid. When the regex 
finds '1211641200', it reads >,'1211641200',< includind the last 
comma. So the cursor will be at the apostrophe before 1214578800:
...200','121457...
--------^

You have to change your regex to not check the comma or use a 
non-matching group like (?<=,) and (?=[,)]).

Note: you're using [,|)] which matchs >,<, >|<, and >)<. I guess that 
you wanted [,)].