It comes on occasionally while at a stop light Or a drive through.
Is this normal?

 

Mine does too. I don't think it's normal. Check your Post O2 readings. You should see ~.04 -.06 while cruising.

I have been monitoring O2 voltages though Ultragauge over the past few months and it seems my drivers side cat may be on it's way out. My driver's side voltages are all over the map. I'm not surprised considering these are aftermarkets have a catalyst a third the size of an OEM set.