Laptop Upright Down Button doing a weird sound once i clink it, please help?

this laptop is acting immensely weird when i click the down button on the device, its only 2 weeks old, i havent used it much, and i dont press hard next to the keyboard, its an HP G62.

the other buttons do normal sounds but when i click this, the sound is like tick tick, when the others are average clicking sounds, i dont know maybe somethign is under it but i doubt it :/

please help