I thought that some places only plugged it or only patched it. My dad recently (couple years) got his tire plugged at a gas station for $5.
Anyway, I really don't remember if the store I bought my tires at offered any such warranty, but if they did, I didn't pay extra for it. And even if it was free, it wouldn't be worth it to drive all the way there when there are relatively cheap ($10 or, in this case, free) alternatives nearby. I'm not driving 20 miles on the 101 through LA on a Sat afternoon just to save a few bucks. And luckily, I didn't have to.
