Turns out, she might not be much of a pal at all...
According to this article, Sigg bottles made before August of 2008 (which my lovely "Earth" Sigg bottle was) have trace amounts of BPA in the lining. BPA is the toxic chemical found in plastic water bottles which has been found to effect levels of estrogen in females.
While Sigg tests show that there is 0% leakage of BPA from their old liners, they also changed the liners of their bottles to new, BPA-free liners after August of 2008. To me, this says they were concerned enough about it to change what they were doing, so I should be concerned about it as well.
Sigg is doing a voluntary exchange of all Sigg bottles with the old lining. Unfortunately, because it is a volunteer effort, you have to pay to send your Sigg bottle back, but they in turn will give you a gift certificate code to purchase a new Sigg bottle from their website. I'm not sure whether the code will include the cost of shipping your replacement Sigg to you, but I'm guessing it won't.
Probably 75% of my co-workers own Sigg bottles because of a company-wide initiative to quit using disposable cups and plastic bottles. Now, I'm in charge of collecting all our old Sigg bottles and sending a mass return back to Sigg for new ones.
By the way, if you own an old Sigg, and you wish to exchange it, all the information you need is in the article above, and you have to return it by October 31st of this year.
Something to think about...