gm labels sometimes aren't strings

Simple type check on label to prevent errors like the one below...

2013-05-15T03:24:06.419Z - error: uncaughtException: stack=TypeError: Object 390 has no method 'replace'
    at ondata (/usr/local/mikey/mikeymail/node_modules/imap/lib/imap.js:338:39)
    at ondata (/usr/local/mikey/mikeymail/node_modules/imap/lib/imap.js:305:16)
    at ondata (/usr/local/mikey/mikeymail/node_modules/imap/lib/imap.js:632:16)
    at ondata (/usr/local/mikey/mikeymail/node_modules/imap/lib/imap.js:305:16)
    at ondata (/usr/local/mikey/mikeymail/node_modules/imap/lib/imap.js:632:16)
    at ondata (/usr/local/mikey/mikeymail/node_modules/imap/lib/imap.js:305:16)
    at ondata (/usr/local/mikey/mikeymail/node_modules/imap/lib/imap.js:632:16)
    at ondata (/usr/local/mikey/mikeymail/node_modules/imap/lib/imap.js:305:16)
    at ondata (/usr/local/mikey/mikeymail/node_modules/imap/lib/imap.js:632:16)
    at ondata (/usr/local/mikey/mikeymail/node_modules/imap/lib/imap.js:305:16), message=Object 390 has no method 'replace', stacktrace=
    at process.<anonymous> (/usr/local/mikey/serverCommon/lib/appInitUtils.js:19:11)
    at process.EventEmitter.emit (events.js:95:17)
    at process._fatalException (node.js:272:26)