I came across this thread while searching for something else, and can verify the tapping throat/chest error exists in multiple places.
  1. Roland taps his throat when addressing Aunt Talitha in River's Crossing, in TWL.
  2. Susannah does the same when addressing Blaine, at the end of TWL/beginning of WaG. Blaine says that insofar as he has a sex, he is male. Susannah doesn't understand, and it is Roland who explains that tapping the throat with the right hand is used when addressing women, and tapping the breastbone with the left is used when addressing men.
  3. In WaG, Roland taps his throat with his right hand when meeting Susan for the first time.
  4. In WaG, Sheriff Avery taps "the base of his throat" multiple times when addressing Roland, Cuthbert and Alain on their visit to the Sheriff's office. This could conceivably be the top of the breastbone, although it's a stretch.
  5. In WaG, Roland and Cuthbert both tap their throats when meeting Susan at the Mayor's dinner
  6. In WaG, Roland taps his throat with his left hand when apologizing to Jonas, "as was proper when addressing an elder"
  7. In WaG, Reynolds taps his throat three times while muttering "Bless the Turtle", seemingly as a ritual of protection against rabies

I suspect King came up with different gestures for men and women (and later elders) on the spur of the moment, just to add a bit of color to the riddles scene, and then forgot about it, later using the simple tapping of the throat as a gesture of respect.

HBJ