Over many years I have become convinced that deep in their DNA, in their genome so to speak, both socks and tea spoons are inter-related at the quantum level.
It is a well known fact that if you put several pairs of socks in a confined space like a washing machine or a sock drawer for a period of time then one of the socks will vanish. I have a theory that your new teaspoons were in fact socks in a previous life and the vanishing socks are simply shape shifted in a separate quantum universe into tea spoons at which point they re-appear in this timeline but only when you are not looking.
To reference the reality of this concept you may be interested in researching the double slit experiment, here
https://en.wikipedia.org/wiki/Double-slit_experiment which proves that by simply observing something you can change its fundamental properties. This is why you will never actually see the tea spoons re-appear when you are looking as by looking you have changed the tea spoon's quantum reality into something else that is not capable of appearing until you cease looking.
The next time your teaspoon count changes I would immediately go and count your socks where I suspect you will find an opposing discrepancy in the sock drawer.
I once read a story about a single Roman chain mail sock that was found in a field and the article didn't mention tea spoons once which I took as proof of my hypothesis allowing me to promote it to "theory" status.
Whatever you do though don't put any tea spoons in your sock drawer as it has the potential to cause an imbalance in the fabric of the space/time continuum leaving you with an infinite number of tea spoons and no socks.