Actually, there was a serious spike in demand. Being alive at the time, and much more than a few months old, I can report that fear and anxiety have a lot to do with it. Everyone was still remembering the price control attempts a few years previously, and part of why that failed was the mbutt psychosis effect that led to everyone to try to get around things, and stock up... (warehouse, overstock, hoarde... whatever you prefer.)
Also, there was a war going on in the Middle East; and we still had the effects of a war in Vietnam underway. People were worried, that everything was out of control.
So, when word came of the embargo... the usual reaction: Fill everything up. Fill every car, keep your tanks full. Because of this, demand spiked and that does create a short-term supply-line shortage. Those took quite a while to fix, so in the meantime, there was a lot of the aforementioned "unofficial rationing".
Most gas stations in Ohio were using the odd-even license plate method. The last number in your license plate: if it was even, you could buy on even days. If it was odd, you could buy on odd days. Of course, that was back when self-serve was mostly non-existent, and the only states that could pull that off during the looming great shortage of 2006 will be New Jersey and Oregon.
Hawai'i will probably survive this, since it's not a hard ceiling price limit, but a price *index*.
