Not sure if this is a bug or just an oversight.. Simply running past Preston can result in him giving you a quest. At first this was ok but now he's starting to repeat quests.. Feel like taking on a quest should be my idea. I should physically have to talk to him and ask if anything needs doing.

Yea i have had the same happen as well, it also happens with random settlers will try to do the same thing sometimes. I think it's just an oversight possibly.

I think that is working as intended I would assume.

I recently got a quest in the castle simply from running around, building and my character obviously being in hearing reach of the radio tower.