Have I got an ignition coil going bad?

[Muleears]

Went out to run some errands today. When I started the X it had a lumpy idle (3.0i). I had my scanner in the back seat, so I plugged it in to see what's going on. Misfire, cyl. 4. I let it run like that for a couple minutes hoping warming up would smooth it out (ambient @40*). No luck, the miss remained. So I shut it off for about 30 seconds. Upon restart the miss was gone. Smooth as silk. This had tripped the SES light also. About half way through my errands (~15 miles) I was parked so I cleared the misfire code and SES light. Finished my errands and returned home with no further problems. Is a coil about to go and working intermittantly? The plugs only have about 1K miles on them. I have no knowledge of the age of the coils. What could be going on?