Hi Faruq,
well, first, I have nothing against ur mechanic but everyone makes mistakes and if he tells u not to worry then I hope u can atleast appreciate the fact why he would say such a thing? Its ur car, ur money and ur time if it stalls - so If I were you I'd worry! (Is this alarming enough for U yet?).
Well, here is what i think, I believe one (or more) valve seals is mis-alinged/loose or not seated properly. So when u park ur car for a long time one of the valve remains slightly open and oil drips into the chamber which is then burnt when u start it in the morning. Here is a test for u, if u have a tachometer in the car. When the engine is at its normal working temperature, rev the engine to about 4000-4500 rpm and then let go. Let the engine speed drop to about 1500 and rev it again. If blue smoke comes out then u have a valve-seal seating problem.
If you DO find a problem - u will atleast know what is wrong. U don't need another over haul immediately but over time the engine will begin to burn more oil. Depends on how hard u drive the car.
Regards,
MSKHAN