Worktops just fitted. Gap between up-stand and wall. Is this normal?

Hi,

I had replacement quartz worktops and up-stands fitted today. There's a bit of a gap between the top of the up-stands and the wall all round. This ranges from about 2-6mm. Is it normal to have a 6mm gap? The fitters say this is because the wall is not straight, but the old up-stand didn't look like it had a gap this big.

Any opinions welcome.

Thanks,

Paul