I think it is rather easy to plagiarize yourself, whether it be with ideas or wording. Different things appeal to different people, and we all have certain weaknesses or habits based on what appeals to us. (One habit of mine I have learned about rather recently is that I use "just" a lot in my writing.) But I guess part of growing as a writer is trying to be more conscious of things that you use a lot...and then trying to strive to be more original while also writing in a style that is distinctively "you."
All that said, I'm actually using a few ideas from my last story for one I'm working on now, heh...but I'm using them in different ways. Still, "oops" for trying to support originality, eh?
Ah well.
