yggdrasill x
forgetting the comic book series (since the Tv series is a stand-alone of a sort)
If you notice Michonne is very untrusting due to the following reason:
1.)Had a hatred for the walkers that were with her,subtly shown when she killed them and
told andrea it was easy for her to "kill" them
meaning that she has had a bad past,with these men...if not men in general for undisclosed reasons.
2.)Helped Andrea in her time of need without any questions.
meaning she has a good standing with Women,and is more than willing to aide them.
3.)Untrusting.
Due to her past,she has learned the hard way that trust= weakness and is better off to avoid it
at all cost,and hopes that her nature alone will get other people to accept her..specifically,andrea.
I actually kind of got the impression that she was more trusting with women over men, but I actually looked at it differently when I was watching it. There were more men than there were women and men are more prone to do unsavory things if the world is the way it is in the show. Not saying that all men would, but they more likely to do something like kidnap and rape a woman, especially since there were only two of them and they were alone. I assumed that was more of their reasoning for wanting to remain undetected initially and for them to be mistrusting.
It's arguable that she could have been more trusting after that didn't happen, but their weapons were taken away and the Governor kept trying to push them towards staying instead of leaving. Then there's her private conversation she had with the Governor about the men having bullet holes in them. I thought those were all good reasons to be skeptical and mistrusting.
Going back to her saying it was easy for her to kill the men, I assumed that she might have said that for other reasons as well. One being that it's possible she didn't want anyone to know she might have been close with either/both men. That could be through being mistrusting or just because she doesn't like to talk about herself. I know people that hate talking about themselves. She also could have said it because they were infected.
I could be totally off base, but there are multiple ways to interpret it.