Generally speaking food poisoning symptoms usually appear 2 - 6 hours after eating the food responsible. (the time frame could be longer depending on the toxin or organism responsible). However, symptoms usually present with nausea, vomiting, abdominal cramps, diarrhea, fever, weakness, etc. It sounds very possible since you started experiencing symptoms a short while after eating that you could have had a mild case. I would suggest to you that you call the restaurant that you ate at and ask them if they have had any recent complaints. If it's a decent managed restaurant they will admit to a problem. However don't be surprised if they don't for their fear of "bad advertisement" which they will eventually have anyway if this was actually the cause.