He tickled my back in a hug?

We did a long full body embrace, hip to hip, for longer than 5 seconds or so and his hand went on my back and kind of did a spider clawing thing that tickled and he just kept doing that...It was interesting. Why do you think he did that? Now he'll randomly do that even if we're not hugging...o,O
He tickled my back in a hug?
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