rowsInserted first and last argument inverted

I have a child of an QAbstractListModel that appends a row using 

beginInsertRows( QModelIndex(), rowCount(QModelIndex()), rowCount(QModelIndex()) );

DebugSrc->addTheMessage( D );

endInsertRows();

where DebugSrc is a QList< SomeClass> that stores the data

I have a Qsortfilterproxymodel attached to this model which in turn is used in a widget that contains a view.

That widget connects to the QSortFilterProxyModels' rowsInserted signal like

connect( SFPModel, SIGNAL(rowsInserted(QModelIndex,int,int)), this, SLOT(rowsInserted(QModelIndex,int,int)) ); 

where 'this' is an instance of the TraceView class (see below)

the signal does some stuff based on the first last index like

while( last >= first ) {

  last --;

}

and it fails. (endless loop)

I attached to the running process and used a 'bt' in gdb and I saw this 

#9  0x0000562f3514c10c in TraceView::rowsInserted (this=0x7fcdb400b650, first=1507, last=1506) at ../../../DebugAnalyzer/Analyzer/traceview.cpp:379

See the values of first and last ???

weird ??? is this correct ????