Well, since they called and talked to you and now know that they WEREN'T really no-call no shows, since you had already resigned, plus there are extenuating circumstances, I don't think you have to worry about termination, if you do decide to stay.
Honestly, if I were in your shoes, I probably wouldn't go back to the same shift. Because, as you said, I'd feel uncomfortable with the whole situation and it would probably affect my ability to focus on my work and do my best job possible. Some people are more resilient than I am, so I'm not saying that you absolutely should not go back...just saying that, if you decide not to, I understand.
It could lead to a bad and resentful work environment if the staff mistakenly think that you're going to run and complain about every little thing, you know?