Why Would a Man I Don't know Very Well Leave me Four-Leaf Clovers on my Desk at Work?

I knew who it was (he left them near my computer early in the a.m. before I got in) although he did not say anything about it. Another co-worker commented that he left me another present...He actually did this twice, which I thought was kind of sweet. I just wonder if there is another meaning to this other than the "good luck" association.