I don't know whether there is any actual correlation or causation here, but I seem to get headaches after drinking newly bottled beer. I'm impatient, and generally start taste-testing newly bottled beers as soon as there is enough carbonation, usually in 3-5 days. I seem to get headaches from these brews, although, as mentioned, I'm not positive that there is actual correlation here, or whether it is mere coincidence. It doesn't matter whether I use extract or grain, and it tends to be more common for lower alcohol beers (perhaps because I drink them sooner as they carb quicker).
Anybody experience something similar?