method:OPTIONS call shows up Earlier than method:GET in the Waterfall

Hi,
I’m running the test on a SPA application. For a Single Page Application, in order to make CORS requests, we all know that the method:OPTIONS call for any Service call will happens first and then the corresponding method:GET/POST call happens.

When I run my tests, sometimes (not always) in the Waterfall, in the Details, the GET and the OPTIONS seem to be interchanged.

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Clearly also the tike taken by the OPTIONS call will be very low as compared to the GET/POST call.
Can someone help with why this behaviour is observed intermittently?
Thank you in advance