Raspberry Pi and HD44780

Setup : Raspberry Pi, HD44780 LCD display 16x2

I do not know how this happened, but my first trial produced something like that

But after rebooting the Raspberry with the LCD connected, the problem seem to be solved...May be it is something to do with overclocking?

link: http://www.rpiblog.com/2012/11/interfacing-16x2-lcd-with-raspberry-pi.html