While being introduced, your extended hand gesture is mimicked, & never returned.Looking for any comments?

I'm introducing my female friend to a co-workers' husband. She stands, & leaning over the table, extends her hand to him.. He, still sitting, open-handedly gestures the "act of a handshake", but never did. Beside being rude,what possible reasons would explain this obviously embarring ..act? Looking for comments from anyone.., paying close attention to what the "guys" might have to say too...~~