Brief headache when blowing nose, normal?

Not exactly normal. A headache when blowing the nose is not really normal. However, a brief and mild headache is less likely to be something serious than a severe and lasting headache. Sometimes a low-grade sinus infection may be aggravated by blowing the nose, and that might explain the headache. If these headaches continue -- and certainly if they worsen -- an exam by your family physician is advisable.