Should you be concerned? Not quite yet. Now in Canada, very low level of radioactive material from the leakage is detected in the air and water. A higher restriction is set on foods imported from Japan, and any food from the radiation affected areas is not permited to enter Canada. I have faith in Health Canada and Canada Food Inspection Agency to keep our food safe :)
What should I do at the moment? Donate to Red Cross and help Japan get over the crisis. It is always a good idea to protect yourself by having an emergency kit at home. Visit GetPrepared.ca to get ideas of what should be in the kit.
What's the deal with potassium iodide?
Having that said, it is not a good idea to take potassium iodide supplement unless there is a dangerous level of radioactive material in the area. 130 mg is 1000x higher than the daily dose (130 mcg) and it can cause damage to thyroid if taken daily. The supplement is to be placed in the emergency kit for "just in case".
Regularly, you would have consumed enough iodine from your daily diet, such as from salt, seaweed, seafood.. If you have hypothyroidism, it would be a good idea to take kelp supplement, which is rich in natural iodine, trace materials and amino acids. An example of a kelp product is Ocean Wonders Kelp; it is in liquid form and you just need to take 1/2 ounce a day for health maintence. It tastes a little salty; it would taste better if you dilute it in water or juice. This product is selling very quickly in the store I work at!