What happens when you forget yourself?

Went to a marathi movie recently called 'Dhudgus'. Didnt like it very much.....In fact didnt like it at all. But anyway....folks wanted to watch it since someone had given them good reviews about the movie. Went to a mall cum theatre to book tickets. Rs 102 was the cost per ticket .  Purchased 4 tickets. Sister, her husband, dad and mom. Gave the cashier Rs 410. 

Cashier: Sir, Do you have the exact change. 

Me: Nope. I dont have change. 

Cashier: Just a moment sir, I'll have to get it from someplace. 

Me: You dont have Rs 2 ? That is surprising....

Cashier: No sir, Morning time.....no change. Just a moment, sir, I'll get it. 

Me: Ok. 

Moments later cashier comes over at counter. 

Cashier: Sorry sir, a bit late. 

Me: Yeah it didnt seem like a single 'moment'. 

The cashier handed over Rs 2 to me and I was off. As I was walking towards my parked vehicle, I realised that, to see the movie, there were going to be 5 of us!!! I had forgotten to count myself!!! When I realised my absent mindedness, I laughed out loud. Started back towards the booking counter to book another single ticket. 

Me (Handing him a Rs 100 note and the Rs 2 coin which he had given me): Here is Rs 102 in exact change. Give me another ticket!! 

I am still wondering how I could forget myself while booking tickets? 

Wouldnt happen again I hope!!!