As some of you will know, I cheerfully make up words all the time. But I'm struggling to think of a word I'd like to exist... I can come up with neither a real one nor a decent substitute.

Can anyone suggest a word or phrase to convey the sensation of realising you've forgotten something that you always remember?

Every week, when I go to work in the Oxford office, I need to put extra cables into my laptop bag. Usually I remember. Occasionally I forget. This is not the thing I'm describing.

When I leave the house without tying my hair up, I clip a hairslide to one of my belt loops. If I'm not wearing trousers, I clip it on the strap of a bag or similar.

Always.

On Sunday, in far-flung south-east London, I reached for my hairslide. It wasn't there. This never happens.

Perhaps it had sprung off? It hadn't. When I got home, there it was waiting. I genuinely can't think of having ever forgotten this before. It's surprisingly disconcerting.