No.
Pressing the event file will lock a event, but i don't know how the Mivue cameras handle events, on my Street guardian cameras 2 files are saved ( 3 minutes each ) depending on when in the current recording i press the button.
So if i am just a few seconds into the current recording and press the button the current file will be locked + the one before it wil also be locked, if the current recording are almost over when i press button then the current one plus the following will be saved.
But i think Mivue operate on the old fashioned way, meaning you only have a short buffer, so you have to be quick to press the button, also i am not sure for how long after the button press the camera will save the file as a event.
Even if you are slow and miss the thing in the actual event file created, then the event recording can always be used as a time marker, and if you have not been driving a lot the event will still be there just among the regular recordings as you was too slow to press the button.
you can always experiment with your event button and see how much buffer it have, for instance when you are parked at a traffic light, press the button the moment the light turn green, then in your event recording you can see in the video how many seconds before the light turn green you have, i think the norm are 10 seconds.
But trying like this can also tell you for how long after you pressed the button the camera record, some are just 20 seconds others a minute or so, just experiment with your camera.
And do remember event files can only be deleted if you format the memory card in the camera or you delete or format on the computer, and having too manu event files can fill up memory card so you have little room for regular driving recordings.
Depending on where you camera are placed it can also be hard to find the button not least if you are driving too, can be unsafe.
Some new cameras have a little remote event button that work on bluetooth, this way you can put that button where it are easy to see and reach.
My street guardian cameras put event files in a folder on the memory card called RO ( Read Only ) but it will also delete those if the RO folder fill up, but there are room for a lot of event files in there, and it work like the normal part of the memory card so the oldest events will be deleted first to make room for more events in the RO folder.