In 4.63 (but not in previous versions), a Reply that does not "Include the text" does not show the signature that will be on the outgoing mail. The signature is in fact present in the version of the message that goes out, just not in the one seen on the screen while you are composing This is different from previous versions (I have the next oldest version on another machine and have done side-by-side tests).
If I do check "Include the text", the signature appears as expected, and the "Sig" box is changed (temporarily) to "No signature" (which presumably prevents double signature attachment).
I liked it better the old way (signature always appeared, even when composing the reply). Any way to get this back?