Technically I don't think what you did would register as a change to the widget itself, but would show as a change to the templates (which would potentially mean any updates to those templates would not be automatically applied at upgrade).

Generally speaking, I try to leave everything the way I found it when dealing with anything out of the box. For widgets with templates (like the Cart widget) I recommend creating your clone and then opening each template on the original widget, changing the widget field and then using insert and stay to clone them as well.

That has been a successful path forward for me in the past.   

I hope this helps!

If this was helpful, or correct, please be kind and mark the answer appropriately.

Michael Jones - Proud member of the GlideFast Consulting Team!