operatorCallExpr() AST matcher not working as expected

Hi,

Given this code snippet,

  1 class Bar
  2 {
  3 public:
  4 int operator()(int);
  5 };
  6
  7 void foo()
  8 {
  9 Bar bar;
10 int i1;
11 bar(1);
12 i1 = bar(1);
13 }

An operatorCallExpr matcher is able to find the the first
CXXOperatorCallExpr at line 11 but not the one at line 12.
MatchASTVisitor seems to skip a CXXOperatorCallExpr node under a
BinaryOperator. Is this expected?