Discoloration on house snake?

[Bottomfeeder]

Hey guys, I just found this weird light-colored spot on my black house snake (Lamprophis inornatus) that wasn't there two days ago, and everyone I've asked thus far is at a loss for what it could be. It doesn't appear to be infected or necrotic in any way, and it's not stuck shed.

Anyone?

 

[Bottomfeeder]

I feel I should add: it's highly unlikely that this is a burn. The enclosure has an under-tank heat pad, but nothing overhead. There's no way this snake could burn its back on the heat pad.