Hi Janine,
I'm not sure that we have permissions set to allow that for members. If when you hit 'edit' in those first 30 minutes after you post, you don't see an option to edit the title under 'Go Advanced' then I'm afraid it's not an option - but from time to time we do go through and fix obvious 'typos' in post titles.
We found and fixed the one you posted today that likely brought on this question
We'll look into the possibility of updating member permissions to include title editing in that half hour window and if at all possible, will enable it.