Possible syntax problem in function-application

I'm getting into trouble parsing the following line from one of the implementers forum scenarios:

event space_gap_event is (ego.space_gap(crosswalk_point, direction: longitudinal) < space_gap_thresold)

The problem is the call to ego.space_gap(), which is a function-application according to the syntax and defined like this:

function-application ::= postfix-exp '(' [argument-list] ')'

This makes the method path an expression, which I don't think it is, because it can't be evaluated. The result is that the parser messes up getting this parsed correctly.