I can't say for sure in your case, but on most keyboards i have such problems, the mechanics are worn out.
Even though your keyboard is "new"-ish, i'd still assume a mechanical problem. But even if not, it is a problem of your keyboard, and the chances of fixing that are close to zero... 🙁
I don't know if visiting the shop you bought that at is really worth the while - with an expensive gaming-keyboard with golden space-bar and bling-bling it would be a bit different - , but if this annoys you, the best advice i can give is: Buy a new one.
(if you consider this, becoming adventurous and checking it by opening it is ok... :-D)
This depends a lot on your budget, if you are a pupil with your spare money coming from selling matches, i...