I have tried it when I handled one at my local shop, and yes the trigger should reset. After the slide goes into battery, let your finger off the trigger and it has a very short forward click into the reset condition. I only did it twice, so two for two.
What I would do, and I am not you, is run some rounds thru it, The recoil may be sufficient to reset your trigger mechanism, or maybe something in the mechanism is just not smoothed out. If when shooting your trigger doesn't reset a few times in a hundred rounds or so, I would then take it back . Or, you can just take it back or send it in now. But I think if the service guys at S&W run a few rounds thru it and have no problem you will be wasting your time. After all you have a test target, so it was fired at the factory. Also, I notice that reinserting that backstrap was tricky and that disconnects the trigger, so make sure yours is install and clicked all the way in place. Good Luck.