LoL!  I learned a long time ago (pretty much the same way you did) that when I grab my PV, I need to grab my e-liquid too!  The best is when I realize - ooh, I'm wearing cargos!  Then, I stuff them both in my pockets & go on my merry way   
 
Love your idea of leaving some in the car but, being in South Florida - it's not an option for me.  I could always buy more cargos though ... hmmmm