This is why FT rocks. I changed my DCA flight today to BWI to avoid the SC construction issues issues and use the PP lounge at BWI (although that Vino Vilo is tempting). I am "only" Plat (but closing in on DM) but a non-preferred A fare flight out of BWI was $194 less than DCA so I paid $6 ($200 change -
$194 fare difference) and then SDC'd to my preferred flight which was booking in P. Thanks for the heads up, OP!