It's probably a little bit of both - less accepted and your imagination. People really are more accepting of two women displaying affection, because it's something even straight women do (where straight men can't show physical affection for one another without catching the gay).
I think part of the issue is that when you don't grow up being read as a gay man, you don't develop the instincts to judge the level of homophobia, acceptance/rejection, etc. around you. In some ways, this is a little bit like how MTFs have to learn how to have vigilance of their surroundings from scratch.
When you were in a relationship with a woman and viewed as female, you had the opportunity to develop a natural and gradual instinct that developed over time in your life. That informed how guarded you felt you had to be, how much you could express affections, etc. We learn these things all the time, simply by being and taken in information around us.
Now, it's a crash course in learning gay male culture 101 - how you're perceived by others, how you recognize or are recognized by family and allies, and so on. You are concerned because you know that you don't have a life's experience to draw on, so you are naturally trying to protect yourself from what can be a dangerous world sometimes.
