Cracking block

[Thoughtclaw]

Hey folks, a customer came to me with concerns about the following situation. We've got two courses of block on top of a wall footing that are fully grouted and have started to form hairline cracks. I'm wondering if the grout is expanding and contracting, and maybe that's what's causing the cracks. They don't look like anything to be super-worried about, but I wanted to get some opinions from you folks. I'm sorry, I don't know how to embed the photos in the actual post.

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[XR250]

When the block is grouted, its moisture content increases and expands. When the grout cures, it shrinks back down. That may be the cause.