[Springtime]

As another commenter mentions it's seemingly the same phenomenon as why 'memory palaces' work for memorizing arbitrary things (among other similarly effective mnemonics) and this article suggests something similar is also occurring unconsciously for random thoughts and gets disrupted by such actions.

Such spacial-based memory triggers I've also seen demonstrated by magician/skeptic Derren Brown, where recall of the participant is manipulated via location-based touch or gestures (both for remembering and forgetting things).