First of all, Hooray and great job! The preview finally works normaly in notes!
I think it would be awesome to add the posibility of leaving a short comment while re-sharing a problem. To avoid possible fraud and mis-interpretation of the feature, you may fix the phrases for the comment (i.e. something like a radio box, instead of text box).
For example: "Nicolae re-shared a problem by Best of NT and thinks it's awesome!" or "Calvin reshared a problem by student A and thinks it's quite challenging." This will be something similar to current Facebook option for the moods.