If you walk a lot it's quite possible your cleats are already worn - I got a year out of ATAC cleats in one pair of shoes, and in new shoes wore them enough for a brand new pair of them to have some slop in a couple of months, but I could hear the grinding when I walked. Look at the contact points and compare them with an online pic and it should be fairly obvious.

My brief flirtation with spuds had me unclipping unexpectedly not infrequently, and the spring tension on mine didn't stay for long.