Bummer. Hopefully the NB's will hold. There should be a little ring of resin inside the caps, which will provide a seal even if the cap itself wobbles a little bit.
I've heard that laying bottles down will make them harder to carbonate, since there's more surface area into which the gas has to dissolve, and it may also be a higher oxidation risk. I haven't really thought much about it as I don't lay mine down, so there may be some folklore stuck in there somewhere (vs. actual physics, which I prefer).