All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
Thank you very much for what you did and you will be rewarded for it, Allaah willing, and this is not an innovation. Rather, it is a beneficial act as it directs the stranger to the direction of Qiblah. Therefore, it is permissible to use the prayer mat like other means in order to indicate the Qiblah for a person who does not know it.
Allaah Knows best.