A Garbage collection bug, or me being stupid ?

OE 11.0 , win32

given the following code

Class A

class temp.ClassA : 
  
  destructor ClassA():
    message "GC delete".
  end destructor. 
  
  method public temp.ClassA DoSomeThingElseFluent():
    return this-object.
  end method.
end class.

Class B

class temp.ClassB: 
  method public  temp.ClassA GetMyClass():
    return new  temp.ClassA().
  end method.
end class.

and this code

DEF VAR a AS temp.CLASSA NO-UNDO.
DEF VAR b AS temp.CLASSA NO-UNDO.
DEF VAR c AS temp.CLASSA NO-UNDO.
DEF VAR d AS temp.classB NO-UNDO.

d = NEW temp.classB().

a = d:GetMyClass().
b = a:DoSomeThingElseFluent().
c = d:GetMyClass():DoSomeThingElseFluent().

MESSAGE VALID-OBJECT(a) VALID-OBJECT(b) VALID-OBJECT(c) VIEW-AS ALERT-BOX.

why is it that I get

yes yes no ?

When you run the code, you get a "deleting" *before*  the valid-object message, so an instance of class A is being deleted - and that instance is the chained call (c). However, in the case of "c", the DoSomeThingElseFluent method still returns a reference to classA which is stored in variable c (i.e. referenced) , so why is it getting GC'd ?

if you take class B out of the equation, ie run the following code

DEF VAR a AS temp.CLASSA NO-UNDO.
DEF VAR b AS temp.CLASSA NO-UNDO.
DEF VAR c AS temp.CLASSA NO-UNDO.

a = NEW temp.ClassA().
b = a:DoSomeThingElseFluent().
c = (NEW temp.ClassA()):DoSomeThingElseFluent().

MESSAGE VALID-OBJECT(a) VALID-OBJECT(b) VALID-OBJECT(c) VIEW-AS ALERT-BOX.
 

then everything works as expected , I get

yes yes yes

in this scenario, the line assigning c is doing the same task as the method in classB, but the outcome is very different.

Maybe I'm being stupid. But this doesn't seem to make sense ...