An unusual date for a Hebrew inscription - Persian Medical Manuscript

In a beautifully written Persian manuscript of Folk Medicinal Remedies that I recently acquired, I found several ownership inscriptions in Hebrew. A previous owner, writes and dates his name in several languages, the Hebrew inscription reads מרדכי .. ב תשרי תרכ"ב Mordechai, the second day of Tishre, 1861.

The second day of Tishre is the second day of the holiday of Rosh Hashanah. I found it highly unusual that there would be a Jew in Iran in this period that would be writing on Rosh Hashanah, a day when Jews traditionally refrained from Work and writing would have been forbidden. There is though the possibility, that though he knew the Hebrew Calendar and could write Hebrew, he erred on the date.

sample page of the manuscript

Inscription is on upper left side

inscriptions are on margins on top and left

sample page of the manuscript