I just did this 2 days ago when my April rate dropped. It was a little strange and I hope I can explain. I called and after confirming, the agent did tell me that since I had purchased the tickets using some credits, that when she gave me a $20 credit back ($10 x 2) into our account, it would retain the original expiration date. I did ask her what the date was and she said the original credits expired in May 2012. I told her, it didn't seem worth it, but she insisted that I should go ahead and process it anyhow. AFter she was done, I looked at the credit bank and to my surprise, one $10 credit expires in September 2012 and the other $10 credit expires March 2013. So it looks like she gave me another 6 months on the "May 2012 expiration" one. So I say, go for it and if you get the opportunity to get a credit, give it a shot because you just don't know how each agent will handle it. However, keep in mind (and the agent mentioned this too), that you only have to use your credit before it expires to purchase, but don't have to fly by that date. Also, you don't have to buy a ticket for yourself either. Since my son in law also got the credit, he doesn't plan to use it before it expires, so all I have to do is log into his trueblue account and purchase a ticket for myself and use the credit and can use my own credit card. (I've done this several times and it's never a problem). The only thing I lose is not getting the bonus trueblue points for purchasing my ticket online though my own account. I'm guessing that you are going to fly JETblue out of DCA. I'm still not happy about that.