Hyundai Repair: 2003 Santa Fe Check Engine Light, gas cap, autozone

Question
My 2003 Santa Fe (w/50k miles) check engine light comes on intermittently.  Started several days ago when it came on during drive to work.  Was off during drive home on the same day.  Next morning, same thing but light stayed on until the drive home the following morning.  I'm pretty sure it's not a gas cap problem because I got burned on that the first year I had the car and I make sure that the cap is securely closed (and light didn't come on until 3 days after my last fill up).  Checked some of the other answers, but didn't find one that discussed the intermittent issue.  thanks...

Answer
The only way to really tell what the issue may be is to have the diagnostic trouble codes read.  AutoZone has advertised they'll do this for free.  

Since your lamp is intermittent, I suspect it may be an intermittent issue with your transmission.  In that case, the lamp is typically off every time you start the vehicle until the problem reoccurs.  If possible, you should have whoever reads the codes to read both the engine and transmission codes.