i wouldn't be surprised if it's your shoes. i know that depending on your footwear, some shoes allow you to build up a much quicker charge then others. also, if you haven't already, you might want to use some sort of anti-static sheet in your laundry. i know it's probably an obvious suggestion, but it has been fairly effective for me.
another thing you can try is switching shampoo brands - depending on the type of and amount of residue it leaves in your hair, you could be a giant charged head every time you step out of the shower and dry off...
