Hello,
After asking the old man how you can acquire his item, the final paragraph of the text reads ‘the door slams shut and won’t be opened again’.
I’m sure it was intended, though I think more is lost than gained, but the player can just click on the watermill again and choose other options and the like.
The fix here, I’m suggesting, isn’t to change that text I’ve quoted. If the player needs to read the event again, or wanted to choose the other option, he may ‘google it’, and be more considered in is choices, respectively.
I haven’t encountered many other unique locations like this, but please consider applying my recommendation to all where applicable.
<3