Strange forum behaviour

Has anyone noticed that if you are the last one posting in a thread you can edit/delete your post but if there have been posts after your post then you can't seem to edit the posts anymore. At least that is my experience.

I wanted to edit a post to replace a picture with a link to prevent copyright issues but for some reason I can only edit a post if I am the last one posting...

I think it's a timed thing, rather than being dependent upon a following post. You can actually sometimes edit even after someone has posted subsequently - leaving all sorts of scope for underhand tricks!

You can edit for 30 minutes, after which everything is fixed.