publishing an http site with https

i have an internal http site which i am publishing through TMG. the listener uses SSL, so it'shttps://external.com publishing http://internal.com. everything is working, except the IE address bar does not show that the connection is SSL encrypted. so i havehttps://external.com in the address bar, but there is no "Lock" icon next to it. is that expected? is the connection actually encrypted?