Mike platelets take about an hour so I am guessing you did whole blood and I am guessing you didn't take Amanda Burden with you to donate.
I always use to joke I am the only one in the East Village who's arms are sore from donating my blood.
When I am sure I am not going to have late in life babies I will donate the rest of my white blood cells which is 2 hour process (each time and you can only do it 12 times) with a needle in each arm but once I am dead no more donations. No donating body parts after I am dead. Enough is a enough.