Ack....lump on retic's neck?

so, i'm posting this for more opinions...This showed up the day after a feeding...4 pre-killed rats (the first three were rather small). At first it was just a soft lump, now there's the two scabs you see. Any ideas? It's soft, doesn't bug him when I touch it, and he's still acting normal.

http://i20.photobucket.com/albums/b2...ps3bfb0e54.jpg

http://i20.photobucket.com/albums/b2...psbccb9045.jpg

http://i20.photobucket.com/albums/b2...pscca66dd0.jpg

Nothing?