This is just another example ...
... of "physical access = complete compromise modulo time".
And this tends to be even cheaper and easier with "Smartphones" (i.e. smallish pocket computers) than with the PC counterparts - and I know quite a lot of people, who use the former to unlock the latter.
Some sanity might just help: This document is important? Encrypt it on a file level and PLEASE close it before letting you computer unsupervised.
On the opposit end of the spectrum, they might have all my "photos" folder. Well, the Memsahib might take issue with that, so not really all.