I like to use examples to illustrate a point. Which is fine, except that I'm not a native speaker and am prone to make a mistake, like anyone else. So, should we make a point of indicating when examples are your own, or pulled from somewhere else, to give an idea of their legitimacy? I'd hate to see my mistaken example sentence go unnoticed (of course I'd edit if pointed out) and be used by a beginner who said, "well I saw it online".
I would say that we should encourage transparency in the sources for our example sentences. It would be very difficult to strictly enforce this, but I think LJU users have been pretty good about being open to edits when it comes to this kind of thing.
We also have to keep in mind that A) non-native speakers may make a grammatically-correct but nonetheless unnatural-sounding sentences, and B) native speakers make language mistakes too, so finding an example sentence from a native source also leaves the possibility of a typo, etc... I would say that both of these types of sentences would also be candidates for community edits :)
When you cite something, you should show where you got it from to show respect and not violate the copyright of the original author.
But you do not need to put a disclaimer that it is your own example. You suggest the purpose of doing it as distinguishing it from examples you pulled from somewhere, but the whole idea of thinking whatever you pull from other websites are correct is absolutely wrong. They include mistakes as well. When you cite something from somewhere, it is the sole responsibility of the citer to judge whether it is correct. The original writer is not responsible to the readers of another website that cites the original. If a beginner uses a wrong example of yours, claiming "well I saw it online", then, it is the responsibility of the ignorant beginner to consider the internet as absolute truth.