The Case of the Missing Model Piece

One of my recent purchases was Khurasan's 15mm Federal Army DIMOG Armorsuit Mk 2. I wanted to beef up Yogurt Town's militia. The model consists of a number of pieces, one of which is the door shield that makes up the front of the driver's compartment:

 When I was ready to spray it with primer, I couldn't find that door shield.  I looked everywhere. After giving up the search, I tried making one out of thin styrene plastic. It wasn't great, but it was serviceable. I took the model, along with some other minis, outside to spray, sprayed them, and then put them in a small box I use to transport minis to and from where I spray. Last night, I sat down to paint and assemble the Armorsuit. Guess what? The home made door shield is now missing! Tiny, individual 6mm infantrymen that were sprayed along with it were all accounted for, but a 12mm x 7mm bent piece of plastic is not. I could have sworn I put it in the box along with the other figures I sprayed. I'm not really in the mood to make another one. I spent a lot of time putting the thing together, particularly pinning the arms and legs to to the body.  I'll take a look outside where I did the spraying, but I wouldn't surprised if I don't find it. Is this some sort of sign?  *GRUMBLE*