i mean, never having a UA test myself i am as unsure as you. But my recommendation is this, prepare for the worst, and that is that you may have to test again, so practice your procedure, and prepare your supplies so that they will be ready. Whats the worst that can happen, they catch you, then you would lose anything anyways.

But fear not, they said you passed, so water it down some more, and just say you stay hydrated.