Your HSV 1 index value indicates that you’ve had HSV 1 way longer than a few days. This is a longer standing infection.
You would be wrong to assume it is was from a recent encounter, correct.
However, if no swab testing was done of the lesions, it could well be HSV 2, newly acquired from unprotected intercourse that you had on 10/15. The antibody test was done too soon to detect a new infection. I would recommend that you retest with an IgG test in about a month and see what’s happening with the HSV 2 index value.