Comments about the film [in one of those social media forums] run strongly along the lines of (mostly) women saying the fear/alert response to anyone (but especially a man) walking behind them is trained into girls [hence it's not a suitable message to highlight assumptions about people based on visible racial characteristics] and others who see no sex- or gender-related overtones in the piece [so of course it's about racism, because nothing else would explain the woman's attitude]. Few on either side appear willing to engage in a learning and/or teaching dialogue.
I think it's cool that someone (presumably) paid and credited two actors who are not white men to make something that is getting an audience of non-trivial size. I have considerable difficulty accepting the filmmaker's apparently intended message of the dynamic between the characters as being motivated in more than a minor way by racial or cultural issues. I have had discussions with people (mostly straight men) who don't seem to understand that following someone fairly closely in an area where there are few others around is an intimidating claim of personal space and implied threat to the person being followed.