Tire pressure monitor worked! Now what...

So I drove to work today in my Prius like any other day... no problems, just another sunny day in the San Francisco Bay Area.

Then I go out to get a quick bite at Subway, and just as I pull out of the driveway, I see the TPM warning light. Damn. I pull over to check all four tires and find that the right rear one is ~36 psi. Which is about 25% lower than when I initially set it. The other tires are all around 41-43 psi.

I drove to a gas station to fill it up back to about 40 psi. I'm just hoping that it's a VERY slow leak and it will hold enough air to get me home. What a way to start the weekend.

 

took it to america's best tire and they said it was a nail too close to the sidewall. not repairable :-(

Since they had no Goodyear Integrities in stock, I got a new Pirelli P3000 instead. Should I have any special concern about having a single mismatched tire? I'd be more worried if it were on a front wheel, but it's on a rear wheel for now.