Strange... though the email alert version of my posting has the proper regsub substitution, the bboard HTML version ends up just replacing the YYYY-MM-DD with " / / " instead of "MM/DD/YYYY". Let me repost the regsub in a plaintext and hope it works:
regsub {^([12][0-9][0-9][0-9])-([01][0-9])-([0-3][0-9])} $pg_date
{//} pg_date