Yes - if the ticket was originally issued as a transit and you wish to change to a stopover then it's a routing change. This was discussed at great length a few months back. The conclusion was that you can b-itch* about the wording all you like, but all airlines and TAs will interpret a change from X to O as a routing change, reissue and change fee.

*(when did this site get the ridiculous censorship that stops me writing that word properly, but which allows me to write bugger, twat and wank? And how do we get it turned off?)