Sorry, a .08, not a .8 --
When you tested, did they tell you .298 of a precent or just .298?
I think in my state you have to blow a .8 to be considered over the legal limit, so .2 (almost .3) does not sound like that much to me. But if you are finding charts that say it is high, talk to your doc. Some people don't have a specific enzyme that breaks down alcohol in the blood very fast (even some whole ethnic groups don't -- the Irish for example). Maybe that is true of you. It's worth knowing if so.
Do you mean why would it not have left your body sooner or why was it not higher?