A 2:
The prohibition of touching small stones while the Imam is delivering Friday Khutbah means to avoid playing with dust and messing around and to listen attentively to the Khutbah, because playing with stones distracts one's attention from listening to the Khutbah. Accordingly, the prohibition does not include what is mentioned in the question, because it is not a trivial act.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.