Sorry, forgot to say what I thought of the lump in your pics, Blueeyes.
Well, it could be orf but it doesn't look typical. You can get orf blisters away from the mouth but not usually unless there are some blisters on the mouth and/or nose. Typical first blisters are under the nostril above or on the lip there, and/or in the corner of the mouth or along the edge of the lips somewhere. Orf blisters tend to be raw and seeping (or crusty if they've dried up) rather than clean spherical lumps, like the one in your picture.
So my money is on something other than orf. If it's just a single lump (with two sublumps), maybe a bite or sting of some sort?
If he's not in any pain with it, just keep a watching brief.