OT I probably can't do that

Today I bought some 4" 10-foot treated posts, and then took them to a
sawmill to be split down the middle.

The owner took one look at them and said, I'm not sure they're big
enough to be held [in the machine].

This despite the fact that on the phone he'd told me twice that he could
do it. The first time 8 or 10 weeks ago when I gave him all the
details and the second time yesterday, when he didn't ask so I figured
he remembered me or it didn't matter what I had, that he could still do
it.

And the words brought back vague memories that iirc, people say this a
lot. It's often the opening words from someone I want to hire to do
something, and maybe from friends too. Memories are still too vague to
give examples.

Has anyone noticed this? Do you have any ideas why people would start
off this way. I'm still trying to remember if I do this.