Yeah, I don't see the big deal in putting them on the right way. Like we mentioned, biphasic defibrillators should work pretty much the same either way, but all views will be upside down.
Just make sure you follow the clearly labelled placement instructions next time. This is no different than using an IV catheter that "expired" a few weeks ago. Will it make any difference in patient care, functionality, or outcome? Absolutely not. Will proctors be able to fail you for using out of date equipment? Sure will. Just play the game, put them on the right way, and move on. No harm no foul in failing an NREMT test station. I failed the paramedic static cardiology test station once. No idea how I managed to do that, and I like to think I'm pretty decent at reading EKGs (for a paramedic at least).