No. Montblanc only began laser-etching an identification number onto its pens in about the early to mid-1990s. A pen made before that — with the 144, that means the earlier series — should carry no number at all. Its absence on such pens is normal and no defect. A plain gold nib instead of a two-tone nib is likewise nothing unusual on these models.
Conversely, the presence of a serial number proves nothing: most fakes carry invented numbers, and the manufacturer will give no information on individual ones. The nib, the finish and the feel of the materials tell you far more. Genuine nibs carry the fineness mark for 14- or 18-carat gold, that is 585 or 750, often together with 14 C or 18 K.
The common fakes of the 2000s usually had no gold nib and were crudely made throughout, so a close look was enough to expose them. That can no longer be relied on: more accomplished copies are now in circulation. In case of doubt, the only answers are a direct comparison with a pen known to be genuine, or buying from an authorised dealer.