Engine light came on?????

What you know, the engine light came on. The car has only got 700 miles. I took it the dealer and was told that it was glitch in the computer system. They did all kind of tests and found no issues. I was not charged for it but Im kind of troubled about it. Any input would be appreciated.

When the CEL (Check Engine Light) goes on, a code has been tripped in the system.  What code was showing?
 
There are tons of things (both minor and major) that can trip the CEL (including just not tightening the gas cap after filling up)
 
I''d try to get the code from the dealer to understand what code was showing.

Thank you. I will ask the dealer about the code.

I would be too Luis.  
They need to find the cause and as long as the PCM/ECU was not reset, the problem should be held in the it''s memory. If they are telling you they can''t find an issue, they are lying.
 
I recently had an ongoing CEL (sometimes called an MIL in Mazda-speak) that was tied to several issues.  All were covered under warranty... +$900 (including 3 days and 2 ''08 Mazda6i VE loaner cars) charged back to Mazda. 
''Sure glad I didn''t have to pay that!!
 
 

The car is acting up weird. see if i can explain myself better-when the car is in idle - like at a stop light. I can feel a jerking motion within the car. But the rpm needle does not move or go up and down. also, the a\c can be on or not. so it has nothing to do with the a\c- I believe. Again, the dealer said that they found no issues and that the engine light went on because of a computer glitch. should I take it back and have them look into it deeper?

Have them look at the engine mounts, especially #3.
They may also need to re-flash the PCM.
Look at the list of TSBs available to see if any seem to fit your symptoms. If so, print out those and "suggest" that these may be involved w/your issue.
Of course, these are all just guesses and recommendations on my part.  Please do not go to your dealer and demand that they do all of these repairs w/o checking first.
 

I have been experiencing the check engine light issue as well.  I took my mazda6 to the dealer a few months back due to an emissions recall which they said was causing the check engine light to come on.  However it has started to reappear recently.  Everytime I reset the gas cap after 8-10 starts it goes out for about 4-5 days then reappears.  Has anyone else ever experienced this?  Could the gas cap be going bad, I have noticed that it backs off

Richard, I understand what you are saying. Thank you for the help and input. vegasguy- I believe I might be having the same issue. I will be in Vegas this weekend. HOT HOT!!!

are you pumping gas every 4-5 days?  maybe you''re not tightening the cap enough/locking the cap - if it has a lock.

vegasguy,  You may be experienceing a problem related to the fuel purge valve (check valve) on the tank itself.  It can cause issues that appear to be gas cap related.

... Ask your dealer to check into that, or look for TSBs that seem to fit the issue.
http://www.finishlineperformance.com/store/pages.php?pageid=12

http://www.finishlineperformance.com/pdf/mazda3/bulletin/01-052-06-1606.pdf
Check out this one... even if your car is newer.

hey Richard, just got to Vegas. HOT HOT!!! car ran excellent and no issues to report. will play a hand of blackjack in your name.

Only ONE??? 
Cheap-skate.   

Made it back in one piece. ok i played more than one hand in your name but lost everytime. do you have bad luck?

:P
I found out the hard way that the house odds are hard to beat, and that all wins are small, but thanks for thinking of me, Luis!!