it slowly seeps down thru the carb into the intake very common...it probably wasn't 100% dry but not enough to get into the motor to start it..... the rest of it in the lines drops back down into the tank slowly which cause dry lines so it takes the fuel pump a few cranks to repressurize the lines and fill the bowls back up..... very common on older cars...... newer fuel injected cars have a check valve that keeps the fuel from running back down the lines..... and fuel cant seep into the engine unless you've got stuck or leaky injectors