I've also encountered this problem but can't replicate it.
I have the same 6 widgets on all my dashboards, with "Recent Notes" being #4. Sometimes upon switching to a different World "Recent Notes" will have turned itself off on that World's dashboard, causing widgets 5 and 6 to shift position. Other customizations remained except for that one widget being turned off.
I switch Worlds frequently, but have only had this happen maybe three times since the March 6 update. I've tried intentionally breaking it -- switching between my Worlds, to collaborator Worlds, rearranging one dashboard but not another, etc. -- to no avail. I haven't been able to replicate any unintended changes.