A couple of websites on recording. Your mileage may vary, and this is not legal advice.

Court Says It's Okay To Secretly Record Conversation If Done For Legitimate Reasons
http://www.techdirt.com/articles/201...41010676.shtml
http://www.wired.com/threatlevel/201...%20Level%29%29

Can we tape?
http://www.rcfp.org/taping/

Once you've recorded, can they get at your photographs?

http://ezinearticles.com/?Does-the-F...rd?&id=4469539
http://news.cnet.com/8301-13578_3-10140373-38.html
http://news.cnet.com/Police-Blotter-...3-6187389.html
http://schlissellaw.wordpress.com/20...out-a-warrant/

Photography Hassles & Rights:
Photography Is Not A Crime
http://www.pixiq.com/contributors/248 (Site original at http://carlosmiller.com/ and may return there in the future)

A final note: If you are required ("requested" in TSA Speak) to remove all your personal effects to put through the carry-on baggage X-Ray, it's going to be harder to retain a electronic device for purposes of recording. Perhaps the reason for TSA having passengers remove all items except for clothing and underwear is to eliminate the possibility of having the encounter recorded.

If you have traveling with a partner, assuming they do not require both members of your party go through sequentially, you have the option of trading the recording position.