Well, I was in the middle of writing this up when the previous three posts were made, but here goes anyway...
What you saw was probably an F-5, which was the recce variant of the P-38. In all probability, this is the photo you saw:
The aircraft in this photo carries what's known as the Synthetic Haze scheme. It's been incorrectly labeled as being PRU Blue or Azure Blue, and the color reproduction seems to be slightly funky but it is the Synthetic Haze scheme. Usually I'd type out a whole explanation here, but I'm tired tonight! And not a bit lazy...
So if you're interested, I'll scan some stuff for you; info on the Haze and Synthetic Haze schemes, including some photos.
BTW, here's a link to a couple of pages on the Little Friends website which deal with the
7th Photographic Reconnaissance Group, the PRG for the 8th AF during WWII. The first page is a listing of the aircraft which were carried on strength, but if you click on 'Gallery' there's some shots of the various birds the unit used, albeit mostly b/w photos.
There were other units that used F-5's in the blue schemes, but I'm not sure off the top of my head which they were.
Again, if you want more info, just give a shout...
Fade to Black...