Haven't experienced this yet on my JK, but my 2006 Dodge Diesel does it quite frequently. Try this little test to determine if it is "sunspots" or a switch malfunction. When you take the key out and the door chime sounds, put the key back in the ignition and lightly bump it a but further in a couple of times. As was noted above there is a little switch deep in the cylinder that gets gunked up and does not always release when the key is removed. Sometimes it takes several "adjustment taps" before the chime will silence. I found a lock cylinder lubricant with a very slender tube (Like WD-40 only smaller) that I can work the lube deep into the switch. You can feel, and depress the switch, when you insert the slender lube tube. For me it lasts for a few months tat then I have to repeat.