I've had a few instances of internet pricing errors that were honored by the website.

The first was at the Anaheim Marriott near
Disneyland. We had an unbelievable rate of $419 for 2 rooms, 6 nights, breakfast each morning of our stay and 4 adult 3-day DLR passes for the amazing price of $419 total. I had called to confirm this rate just a couple days before my arrival and I canceled a reservation at another hotel when the reservations operator assured me that if that was the rate I booked, that was the rate I was getting.

The second was a reservation thru USAirwaysVacations for 4 nights at an SSR studio w/
DDP for 2 adults at a total of $153 plus the cost of park tickets. Not $153/night...that's 4 nights with dining! I booked it and then called 3 times to make chnages to the ressie and to make sure that it was not an error. The first two TA's just told me that they get great discounts because they book large blocks of rooms. The third TA agreed that the rate was unbelievable. Two days later, the rate was changed on their website but my reservation was never altered and I was not charged any additional money.
Now neither of them had to honor the prices from their websites. Both of them had disclaimers that they were not responsible for listing errors. It was a testiment to good customer relations that those companies honored their published rates. I have yet to return to the Marriott in Anaheim but I have been a Marriott guest numerous times as a result of this experience. And although I try not to fly USAir, I have booked vacations with their affiliate if I found a good rate for a planned trip.
Bottomline: Call Priceline. You don't want any surprises later on. If it's a mistake and they can't honor the rate, you will still have time to find a better rate elsewhere. If they honor the rate, you will have nothing to worry about.