I created a mailing, assigned 4 target groups to it, and checked the box that says 'Subscriber has to be in all target-groups'. Saved and all was fine.
I logged out, logged back in, and viewed the mailing: the checkbox was unchecked.
I really think the checkbox should be sticky (in my case, remain checked). Here's why: I edited my mail content and hit save, not knowing the checkbox had unchecked itself. the mail was a date-based mailing. the next day i had unwittingly sent an email to 40,000 people

i'm using 5.3.0 on linux.