I would be very reluctant to give a stranger my home address, even though they seemed to be a solid citizen that I didn't mind selling my gun to. Remember that a piece of paper lives forever, and until you move you've made yourself a burglary target.
Even if they're honest, I don't want their ex-con brother in law, doper teenager, or perhaps unsavory casual acquaintance, to have the thought "Hey, this guy you bought it from probably has other guns too. Let's see what he has. When he's not home...". It happens.
Same reason not to have a gun cabinet--if you do, suggest you get rid of it--or tell everyone at work that you own guns, or leave gun magazines lying around to be seen by the carpet cleaner, the furnace repairman, the plumber, or anyone you don't know. Why advertise that your house is number one on the ripoff list?
Sorry if this is off-topic, but I just had to speak up.