It looks like you sent that package by expedited parcel so you if you check the tracking number on the Canada Post and/or USPS website, you should have more information about where the item is right now.
Then contact your buyer with the tracking number and tell her where the item is. I would also explain that shipping from Canada does take longer than shipping within the U.S...The buyer might not have even noticed that you are in Canada.
Once they receive the package you can ask them if they would consider revising their feedback. If they will, you have to send them a feedback revision request.
I don't know if you already gave the buyer the tracking number but if not..you should always upload that number to ebay so that they can check up on their package. If you use paypal shipping to print their label, the number uploads automatically.
I find that buyers are more patient if you write them after you've sent their item and give them an estimated arrival time. In the case of international buyers, you can also mention that there may be delays in customs or at least mention that the package was sent by Canada Post just to remind them that you are in another country.
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