If there's a message in what's left, it's not obvious to Keltham without knowing what other spells he has. At least, not unless he has to negotiate prices twice today. Negotiate prices urgently? Hurry up and negotiate a price on info already?
Or, "They would otherwise cheat you, if you didn't have this spell, worry more about being cheated?"
Should he tap himself with the spell that's probably Early Judgment... no, actually he shouldn't do that until he's around somebody with a Dispel, Keltham doesn't think. It doesn't have to be Early Judgment. Keltham doesn't need to say that he already suspects what the spell does.
Keltham thinks. Not just about spells. He has queued things to think about.