'Service Engine Soon' light..

Hi:
Having a 'new' toy (Buick Century 2000) I made a mistake (?) trying to 'fix what ain't broken'.. Knowing that the car is 3 years old, I wanted to check the condition of the air filter. After some strugle with the rubber intake, I checked and found that the filter element was clean. Had a hard time to re -instal the assembly.. It just is not as easy as it was with older cars..
After driving for about 200 miles, the warning 'Service Engine Soon' light eliminated and stayed on (no flashing). I was concerned of course.
Took the car to our college automotive technicians who have the computer attachments/scaners. They pointed out to me that the fault was something like..Main Airflow sensor..
I asked them to make the warning light go away which they did. The light now comes on only for one second on the dashboard, than stays of, until the next start.
My question:
Should I worry about that, an/or is this now fixed? You know very well that if I go to dealer, they will claim that I need to change that and that.. (:-(
Thank for your cooment on this..
Peter Solarik

Mass air flow sensor maybe? Did you unplug it trying to check you air filter ? I'd check the plug wiring to it or if you took the air tube off see if it's not broken or leaking.

Mass air flow sensor maybe? Did you unplug it trying to check you air filter ? I'd check the plug wiring to it or if you took the air tube off see if it's not broken or leaking.

Thank you very much !
On the advice of college automotive technician (employee) who showed me how to properly remove the rubber air filter assembly tube, I unplug ed all the electric/sensors connectors to this rubber tube.
Even with this step I had hard time to slide the tube back in the place afterwords.
(I think that I know now how to go about it).
It could be that I did not re - install the rubber tube properly. However, the light 'Service Engine Soon' does come on just briefly with the others (one second) when I turn the key on to start the car.
Since the technician turned off the light (on my request) with his hand held scanner, and the light comes on only briefly during start, is everything all right now?
I really like the comfort and all about this car, it is only some unneccessary gimmicks such as ...'low tire' warning (for idiots), that bothers me about this car.
I used to own Mecedes 300 D (learned the hard way not to buy imports anymore). Then I owned Olds Cierra 1989 (also good car).
This Buick, if it will last as long as its reputation claims should last me (with proper care) at least 6 years (?)
Thank you very much again for your input on 'Service Engine Soon' 'problem'
Peter Solarik

Yes, the light should come on with the rest of them at start up that is a bulb check. As long as it goes out your o.k.