She thanked me when I intervened, so yes, I'm confident that she was uncomfortable.
FWIW, it wasn't interactions between co-workers who know each other. The outing was a dozen or so male employees of a tech company who were later joined by four employees of a recruiting company who provides us with candidates. The only female in attendance is an employee of the recruiting company. She was the recipient of all the attention in all 3 cases. I believe only 1 of the 3 guys who crossed a line had ever met her before.
Potentially also of note is that none of the male recruiters said anything. It may be that they generate a lot of business from us and weren't willing to say anything for that reason. She definitely seemed to be the junior member of the team.