Got lucky last night....

Took a walk up to my shop last night, and for whatever reason I happened to be looking at the driveway and at my feet I found a spring clip. As new and shiny as it was I knew it had to have come off my machine.

Now, fearing I had lost something in the yard, like the pin the clip was holding in I now forgot what I had went to the shop for and started checking everywhere for the missing parts.
Thankfully the pin that the clip secures was still in place, barely. It was on the lift arms for the mower deck. What I don't understand is how it came to back out. The clip on the other side was not in any danger of coming out and seemed to be tight. Hell the clip I found in the driveway was not bent or misshapen at all. I will take a pic of this pin this evening and post it here so you all know what I’m talking about.

If any of you have had the same issue, please fill me in. I am wondering if I should safety wire some of these things in place. Cheap insurance, since I may not be so lucky next time.

Thanks!!!