No, it's not a big deal. As long as there is nothing blocking the nozzle.
A bottle pressure valve is a good idea. Try to keep it between 900-1000psi. If the bottle heats up in the sun, the pressure blow-off disc in the valve will pop, and all of the nitrous will be vented out of the bottle in one big swoosh.
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Moxie Racing
The Nitrous Oxide Information Site