Unless you purchased a ticket and used the code, I'd assume that you can check prices as much as you want and book later (assuming there are still seats and the promo is still valid).

I booked a $427-$200 out of RFD all in, then it dropped about $20 with the e-cert but I ended up buying a ticket for a friend out of MSP so I have some company with the e-cert

It's amazing the points you rack up with the line 'hey baby, want to spend the weekend in Paris?'. I think I'm almost back to even with ma woman now. ^ Well, until I screw up again.