FLASHING Check Engine Light (Sometimes)

Currently having a strange problem. I own a 2002 X with roughly 83K on it. A few days ago, I was towing a trailer, nothing on the trailer and it was not really that heavy. Made from steel mesh, anyway, I was accelerating with the RPM's staying between 3000 to 4000. The Check Engine Light started flashing!!! But only did it for about 5 to 10 seconds. It stopped when I started slowing down. I sped back up again, it started flashing again for another 5 to 10 seconds until it went off. I turned off the hwy, tried to make it happen again, but could not. Accelerated quickly with RPM's in the high 4's, but no flashing light. Finally, last night, it flashed again on the same hwy I was on a few days ago. Once again, I was accelerating, kept the RPM's at exactly 3000, going about 60 mph and towing the same trailer. It only flashed for about 5 seconds until it went off. Did not come back on and has not since. Since then, I have driven on the interstate going 80 mph with no problems. When the light flashes, I notice no difference in the engine, no strange problems, no smoke or noises. Anybody have any idea what could be causing this??? Thanks!!

Have the code read. I think the computer stores the last codes it flashed. Autozone reads them for free.

If it's flashing, that indicates a misfire and should be attended to A.S.A.P. From your owner's manual (you do have one, right?):
Malfunction indicator light blinking − An
engine misfire has been detected which
may damage the emission control system.
To reduce or avoid emission control
system damage:
O do not drive at speeds above 45 MPH
(72 km/h).
O avoid hard acceleration or deceleration.
O avoid steep uphill grades.
O if possible, reduce the amount of cargo
being hauled or towed.
The malfunction indicator light may stop
blinking and come on steady.
Have the vehicle inspected by an authorized
NISSAN dealer. You do not need to
have your vehicle towed to the dealer.
CAUTION
Continued vehicle operation without
having the emission control system
checked and repaired as necessary
could lead to poor driveability, reduced
fuel economy, and possible damage to
the emission control system.

Welcome back from vacation OffroadX!!

Thanks, it wasn't bad. This board is slow enough that I didn't miss much.