I'm at work right now, so I can't check, but I seem to remember Kenny Hall (a mandolin player from northern California) singing a song that had that phrase in the chorus. Did your grandfather-in-law have any lyrics, or did he only do it as an instrumental? I *think* (no promises now) that it went:

Hi lee hi low, watch the little doagies all day
Hi lee hi low, watch the little fellers at play.