This came up about a year ago when post-edits started getting moderated.

Sometimes a moderated post will be put up, and then the poster will alter it so that language which would have gotten the post rejected gets into it.

Apparently once a post goes up, the TER software can not distinguish between moderated and non-moderated posts any longer.

So, TER made a decision to inconvenice the non-moderated people rather than to allow moderated people to alter their posts without another round of review and attendant delay.

One way around this is to append a response to your previous post pointing out the change that you intended to make.

Otherwise, just wait an hour or two and your edited post will appear.

Or better yet, carefully proof your original post to edit it to what you want it to say.