What'd you clean it with? Hopefully not soap.
Perhaps if you sprinkle the stone heavily with corn meal....and bake at about 325 for an hour until the corn meal turns dark brown. Cool and remove the corn meal.
You ask is this normal? nope! But I don't know how much oil you spilled on it...normally you don't "clean" a stone but for leaving it in your oven...but you say it smoked for 3 hours??
I suspect something else is going on....perhaps there is something in your oven?
Linda C

Thanks for your questions. I have read and reread the dos and donts about care of the stone so I did not use soap. Also, I did use cornmeal when I baked the pesto pizza when I used the stone for the first time. When I baked the bread (three loaves) I used parchment paper on a baking sheet and placed on the stone. It seemed like a little much to me but I went by the bread book instructions. When you suggested that something else may be going on maybe that is the something else. I will say that pesto pizza did have a lot of oil but that should not haved smoked for long I wouldn't think. If anyone has an idea about this I would appreciate hearing. In the meanwhile, I will leave the stone in the oven the next time I use to see if it smokes without the baking pan with parchment paper on it. Thanks again, Bev

Parchment paper is silicone based and can take the heat. It will not smoke at that temperature.....wax paper might smoke if placed on a stone (never tried that). The smoke is most probably coming from oil that has worked itself deep into the pores of your stone. You didn't say if you had pre-baked your stone before you started using it for the first time. Just bake it alone in the oven until it stops smoking and it will be fine the next time you use it. You were probably very close to burning it all out the last time you used it.

Dan

When we had the same problem, instead of the oven we did it outside on the gas grill. Turned the grill on high, closed the cover, and let it smoke until it stoped. Took about 1/2 hour. No smoke in the house this way.

Thanks to all the replys. I left it in the oven last eve and it did smoke some more but not as much. I will be happy when it is good and seasoned. Thanks, Bev