"Retainer" was lying on the ground embedded in the grass so I put it back where I thought it was supposed to be. When you return a misplaced cache to its hiding spot, you run the risk of replacing it to the wrong spot. However, in this case, I was fairly confident of the original hiding spot because of the name of the cache and because there was only one crevice where it would fit.
I took a gamble on "Wile E. Coyote Can Do It in Less Than 30 Minutes" because this cache was still temporarily disabled at the time I went to look for it. I wouldn't have tried it if I wasn't already in that very same strip mall for another cache. Well, guess what? It was there! Apparently, the cache owner put in a replacement cache just before I got there. Lucky.