Copy / PasteSpecial switches to other sheet

The code below switches to Outsheet as soon as it hits the PasteSpecial line. I can make it work by adding "Sheets("InSheet").Select" after each PasteSpecial, but is that really necessary? Oddly, if I step through with the debugger, it works fine, but as soon as I hit F5, it switches sheets.

    With Sheets("OutSheet")
        Rw = 4
        EndRw = Range("A" & Rows.Count).End(xlUp).Row
        OutRw = .Range("D" & .Rows.Count).End(xlUp).Row + 1
        EndCol = Range("A3").End(xlToRight).Column
        Do Until Rw > EndRw
            If Cells(Rw, 41).Value > "" Then
                Range(Cells(Rw, 41), Cells(Rw, 44)).Copy
                    .Cells(OutRw, 4).PasteSpecial (xlPasteValues)
                Range(Cells(Rw, 46), Cells(Rw, EndCol)).Copy
                    .Cells(OutRw, 8).PasteSpecial (xlPasteValues)
                OutRw = OutRw + 1
            End If
            Rw = Rw + 1
        Loop
    End With