The idea of a fallacy in philosophy/logic is a very targeted idea. Fallacies pertain only to arguments, which are sets of premises with conclusions that ostensibly follow from the premises. Fallacies occur when an argument follows a course that doesn't guarantee validity. Validity is defined as impossibility that premises are true and a conclusion false, where that "and" is conventionally treated as an inclusive "or."

What you're describing is simply people interpreting something different than someone intended it. There's no generalized way to always avoid that, and it's bound to happen more often when we're talking about behavior that's not common--which could include someone intently gazing across a street from a particular vantage point. We simply need to explain the difference between interpretation and intent in an understanding manner.

This is probably an informal fallacy.

The kid in question thought:

1. That person is looking in this direction
Therefore
2. That person is looking at me

As you can see there are many many objects to look at in any particular direction. So, yes, the kid committed a fallacy. I hope you didn't have a scoped rifle with laser sights.