I think the term de ja vu' is used for either situation: remembering and feeling like we've been there before, or something like this has happened before... whether good or bad?

I can have strong, good memories... without them being flashbacks. IDK but the term "flashback" is always connotating negative. And the term "trigger" also has the negative connotation, yet, we can be "triggered" into remembering good stuff, too.