Why do you mention that a certain work or post is copyrighted by you and under a certain licence?
PrevNode LinkNextFirst of all note that IANAL/etc. Anyway, I try to give explicit and more permissive licences (e.g: Creative Commons ones) to all my posts and works because otherwise they are “All Rights Reserved” by default and so under much more restrictive implicit licensing conditions. I know that Ashleigh Brilliant got copyright to apply to relatively short sentences (which most of my posts are longer than them), and that there was a court decision that made it a violation to sample and reuse even a single chord of a copyrighted song. So there may not be a minimal limit to how substantial a copyrightable work can be.
Most of the licences I use permit some use that will be normally be forbidden by default, so you are better off, and it is better to be safe than sorry.
Also see: