Have you declared it as a library? If so, you can use OleView utility to check output in your .tlb file.
I receive this warning only if there is no library incapsulation for this interfaces.
The other way to avoid this warning message might be using the following trick:
struct SMyObj{
IMyObj2 * iobject;
};
interface IArrayMan3 : IUnknown{
[helpstring("method GetArray")]
HRESULT _stdcall GetArray2(SAFEARRAY(struct SMyObj*)* pArray);
[helpstring("method PutArray")]
HRESULT _stdcall PutArray2(SAFEARRAY(struct SMyObj*) pArray);
};