Why does the spoolfile have single quotes around it?

[neilsmith <..hidden..>]

This is the output from the table "status":
--------------------snip--------------------
select * from status;
trans_id | formname | printed | emailed |      spoolfile
----------+----------+---------+---------+----------------------
  10165 | check    | f       | f       | '121235313411426.ps'
(1 row)
--------------------snip--------------------------------------

Why are there single quotes around the file name ?
This invalidates the url found under check printing.
Thanks for your help.
-Neil