Is it bad to copy and paste from your SoP to other questions on a grad school app?
Well, eventually this is an opinion poll but I would predict the odds is at your good side. I've been reading many application packages in a graduate school and situations like yours do not bother me for the following reasons:


The statement of purpose is supposed to be the best thought out piece of your application. For that reason I think it's sensible to reuse the materials.
You have slightly revised the passage by adding some contents to the beginning to make the whole answer stand alone fine. That shows thoughtfulness.
Some committee members may even advocate for you for being able to include some crucial information in the statement of purpose without being asked.


So, I don't think it's a deal breaker. If you want to tackle this kind of situations more confidently, provide a shorter synopsis in the short answer, and note that a detailed description of the leave is included in the statement of purpose. This would improve the coherence between the application components.

Good luck.