Got Milk?
Okay, now that it out of the way...yes, it could be damaged. While I am pretty sure that milk is a base (base vs acid) so that it won't be eating away at your components causing them to rust like orange juice could in theory...anytime liquid gets into electronics there can be issues.
Since you have already tried using the laptop and say it seems to be working fine, I would assume you left it to dry out for several hours? While there will likely be some residue of the milk inside of the laptop since the liquid was not something like distilled water, you may have lucked out and not have gotten any of that residue inside of the important areas.
You mention the touchpad click does not work, do you mean the sound does not happen or the button does not work at all?