You say "many people"? It's not very familiar to me, though I'm sure I've at least heard it. I think your belief sounds about right. Point out the mistake, hold him accountable for it, ask him to explain it, whatever.
Tide someone over - make it last until the next regular... meal, paycheck, whatever.
If a college student is doing student work-study, but only gets paid once a month, her mother might send her a little spending money in the third week to tide her over until her next paycheck.
We're in the car and not going to reach our desingation until about 2:30, which is way past the time we usually eat lunch. So I have a candy bar to tide me over (control my appetite) until we arrive and can eat.