With respect, and I'm not saying this applies to you, but I'm poking fun at the people throughout this thread who keep saying that these incidents should be reported to HR, or we should get HR involved, or some combination.
In my opinion, these are comments from people sitting comfortably behind their chair at insert Fortune 500 company here, who have no idea what it's like to work at or run a startup. The suggestion that said startup should go out and hire an HR consultant is equally ridiculous.
That's not to say "lawyer up" isn't good advice, because I think it is, but startups routinely hire lawyers; they do not routinely hire HR people.
My startup was almost 4 years old and well past a B round before we ended up hiring our first HR person.
So, to be clear, what I'm saying is if the problem is bad enough, you should consult a lawyer. If it isn't, you should handle it in-house with common sense and perhaps some advice from advisors/lawyers. At no point do I think it's reasonable to advise someone to go out and hire an HR consultant.