I can't bring myself to trust a plug in one of only two tires contacting the road, but then I'm fairly risk-aversive... :-[
Yes, I know it can be done and the odds are good the tire will be fine if the plug is installed properly, I just can't do it...
[edit: I've got a BT010 rear with 1300 miles with a nail puncture sitting in the garage taking up space. I replaced it the next day after I discovered the puncture. So, I've been there and that's what I did. BTW, good job checking your tires and discovering a potential problem!]
As an ex-motorcycle courier, I can tell you from vast personal experience that the mushroom-style plugs used w. the sealant/glue/whatever that stuff is work wonderfully. It is gross exaggeration for people to talk about how your very life hangs in the balance, etc. Over my time in Aan Fran as a courier, I'd say I used plugs maybe 30 times or so, and I've also used them in regular riding maybe 4 or 5 other times in teh 22 years I've been riding.
The most catastrophic failre I had was a case where the hole was too big to get a seal, and the tire wouldnt hold air for any meaningful amount of time (like, totally flat in about 5 minutes). I had a few others leak slowly, to where I had to redo them, and that's about it. All of the messengers I rode with did the same thing, and I've never heard of a single catastrophic failure caused by a leaking plug. I mean, what could possibly happen...the think breaks off or comes out, and the tire goes flat. Hardly life or death there...it's not like it's gonna cause explosive decompression.
Anyway, now that the original poster has the leaking tire off, it's ready to be patched from the inside (which is for sure the best way to patch), so that it can be put back into service when the new one wears out.
If you guys have tires with only 1,000 laying around just let me know how much you want for shipping. Mine has no center tread at all, the cords are starting to show. so a patched tire will be alot safer.