You're not doing anything wrong, of course, but keep in mind that your bank (even though it's not required to) may file a suspicious activity report (SAR) through FinCEN's BSA e-file system. Let me explain. Although $10,000 is the threshold for the reporting requirement under the Bank Secrecy Act, passed by Congress in 1970, and adjusted with the Patriot Act in 2002, a bank may report any activity it thinks is "suspicious." Your stack of greenbacks may spook the teller.

RNE, asking, Should you seriously worry about it? I wouldn't. But I'd also keep a document trail of the purchased and cancelled flight.