It is not housed with other geckos, and I don't believe the heat lamp is UV...it is a darker bulb reptile light. It was the one the pet store recommended!
No, the blue ones shouldn't cause burns since it doesn't emit UV light. It's worth mentioning, though, that a UTH is a more appropriate heat source for a leopard gecko and that lights shouldn't be left on at night.
Personally, I do find that sore/wound concerning because there is not an obvious reason why it is there and it looks very inflamed. If it were my gecko, I would take it to the vet. It could be an external parasite, bacterial infection, or fungal infection.
Unless you can think of how an injury could have occurred.
It does seem fairly red, however, he is getting ready to shed, which may make it appear more red/inflammed than it actually is. We will watch him for another day or so and see if it gets any worse or better.
That looks a lot like a burn to me. I'd check for hot spots in the enclosure and make sure he/she isn't climbing anything and getting too close to the heat source.
I used low wattage black lights to boost ambient heat for a little while, but was concerned about the potential for burns. I've since moved my leos to a warmer room and use a UTH on a thermostat as their sole heat source. They seem to be doing really well with that.
Keep an eye on your son's gecko and check for board certified exotic vets in your area, just in case the sore gets worse instead of better.
I agree that it looks like a burn. I don't recommend using any overhead lighting at all with leopard geckos unless your house is under 65 degrees all day. I would very thoroughly and carefully spot check temps in your tank using a probe thermometer or Infrared Temp Gun and make sure no where is over 85 degrees except for the floor inside the dry hide that is over his under tank heater.