Hello Paul - welcome to the forum. Omega tolerances for the date change are rather wide, and Omega specs for the Cal. 2500 allow the date change to be + or - 10 minutes of midnight. As someone who services watches, I find this to be a very liberal tolerance personally, and for the type of mechanism in this watch it's not difficult to get it much closer to right on midnight (within a couple of minutes).
The type of date mechanism can affect how it switches, and to a degree how consistent it is and how accurate it can be. This is a semi-instantaneous date mechnism with 2 springs involved, and the tolerance is there because these are not always consistent - but again 10 minutes either way is pretty loose.
Although I would not let one leave my shop like this, I don't think I would go to the trouble of having the watch opened to fix it. It's an easy fix for any moderately skilled watchmaker - open the case, remove the movement, remove the hands, reset the hands so the flip is close to midnight, then assemble and pressure test. Personally I would leave it until your first service, but keep in mind the watchmakers at Omega will be working to the same tolerances of +/- 10 minutes...
Cheers, Al
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