Chevrolet: Check Engine Code, spark plugs, spark plug

Question
I have a 1998 Malibu with a check engine light problem.  The problem is that my check engine light is on and the code is a P1374 which from what I have found is a cylinder 4 misfire.  My mechanic tells me that theis code is an ignition ground out and the reason it is on is because I changed my own spark plugs.  Apparently when I unplugged the wire from the spark plug it arced to the computer and register a false code.  Is this even possible?  To me it sounds like they are just making things up because they think I am stupid.  Please let me know what you think.  Thank you.

Answer
Chris ;
Hi -well you could have caused the computer to show a false code , but it should come out just as easy . it might go away by itself in a few days. I would wait to see if it
will go away in a few days. if not there is no reason for it to be removed with a meter . ok