Actually there's a bug while managing the live jquery event to init mb.tooltip on ajax loaded element that prevents to specify a a specific DOM element for the tooltip.

A Workaround is:

line 37:

if (this.options.live)$("[title]").live("mouseover",function(){$(this).mbTooltip(options);});

should be:

if (this.options.live)$(".tuaClasse[title]").live("mouseover",function(){$(this).mbTooltip(options);});

linea 38:

var ttEl=$(this).is("[title]")? $(this): $(this).find("[title]");

should be:

var ttEl=$(this).is(".tuaClasse[title]")? $(this): $(this).find(".tuaClasse[title]");

I hope to publish soon a bugfix.