Keys still work after release

Hello,

I am using laptop Acer Aspire V3-571G and for quite some time my keyboard acts really strange. The main keys that give this problem are W and spacebar. This only happen during gaming when either of those keys has to be pressed for a really long time(W for walking for example) The problem occures after I release the key - it continues to function(character will keep moving and pressing S to go back will halt the character in place for several seconds until the effect is gone and then starts walking backwards as normal)
The laptop is less than an year old and I am sure nothing has been spilled of the keyboard. Is it possible to be a software problem? Or is it hardware as I suspect?