I was able to figure out what was happening after all.
All I had to do was change the order I made the connections. Apparently connecting the mouseMove event after the plottableClick event disconects plottableClick
this does not work:
connect(ui->customPlot, SIGNAL(plottableClick(QCPAbstractPlottable*,int,QMouseEvent*)), this, SLOT(findPoint(QCPAbstractPlottable*,int)));
connect(ui->customPlot, SIGNAL(mouseMove(QMouseEvent*)), this, SLOT(setPlotCursor(QMouseEvent*)));
// making this connection apparently disconnects the plottableClick connection.
this works:
connect(ui->customPlot, SIGNAL(mouseMove(QMouseEvent*)), this, SLOT(setPlotCursor(QMouseEvent*)));
connect(ui->customPlot, SIGNAL(plottableClick(QCPAbstractPlottable*,int,QMouseEvent*)), this, SLOT(findPoint(QCPAbstractPlottable*,int)));