At one time I was about to get mentored and taught forest craft. I hadn'd planned to learn it at that time so I was a little unsure at first if I should accept the mentorship. I waited a moment, picking neither yes nor no while I was shown how to create tanglecloth. I'm not sure of the exact timing, but the moment I cancelled the offered mentorship, the window which offered to learn the skill popped up. 

Is it possible the game's prompt to offer the second window "remembered" that the first window was still open or something?