My DH did something simular to me 4 years ago.
I had Amerauracana chicks that were just feathering out in the brooder room. He got a tiny blue pullet egg & put it in the brooder room for me to find.
I didn't get too excited about it, but I did hunt every nook & cranny looking for any way that a hen could have gotten in that room at the barn. Drove me crazy!!!
He thought it was hilarious!! He told everybody that I thought the chicks were really special that they started laying so early. I just let him have his fun.
Then, a few months later, I walked by one of my OEGB breeder pens & saw an egg. I did get excited about that, I had to go check & it was a white egg shaped rock!!!
I acused him of planting that one too. He swore he didn't & he didn't get that "look" on his face so I guess the chickens just dug it up from the ground. I still have that rock.
Of course he got a kick out of that one too.
I still haven't gotten him back, he is always on guard, since he pulls stuff like that every chance he gets.
Let him have his laugh, you might get a chance to pull something on him later on...when he least expects it!!
If not, it will become a fond memory for him to get a chuckle out of for years to come.
Jean