has occurred vs had occurred

[Daemon99]

In one of the dictionaries (WordWeb), the meaning of deja vu has been given like this.

deja vu = The experience of thinking that a new situation had occurred before.

Can someone please tell me why past perfect is used instead of present perfect?
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Non-native speaker of English
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I intend to live forever - so far, so good.

[Mister Micawber]

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No good reason; the writer obviously wished to stress the difference in time between the two 'situations', but it is unnecessary, I think.
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Native English teacher at Mister Micawber's