I definitely wouldn't have reacted if I was personally involved in this. However, I do think it's worth pointing out how masculine pronouns can wear a girl down over time / create general awkwardness (ie: Send your "web guy" over).

I'm generally not bothered by subtleties, but then I realize that what's subtle to me as a woman is entirely invisible to men.

If the guy prefers masculine pronouns, it doesn't make him a sexist exactly. But it would imply that he doesn't experience the subtle discomfort in his everyday life. So, it's worth pointing out. In a chill way, if possible.