Humour through repeated use of a construct, with a final variation?

Your illustrations could be examples of anacoluthon, "an abrupt change in a sentence from one construction to another which is grammatically inconsistent with the first"; or under the more general classification of metanoia, which is the breaking off of a sentence in the middle to correct oneself. In your examples, the speaker has apparently realized he may have exceeded the bounds of propriety by assuming too much in his flattery; he then backs off and requests permission to be so familiar. Calling this metanoia tests the boundaries of the definition a bit, but I don't see why breaking off to ask a question should be out of bounds.

is it a callback?

A callback is a reference a comedian makes to an earlier joke in a set. Callbacks are usually made in a different context and remind the audience of an earlier joke, creating multiple layers and building more than one laugh from a single joke. When used at the end of a set, callbacks can bring a comic's routine full circle and give closure to the set.

In comedy writing, the construction is known under the larger grouping of the “the rule of three” in that such jokes require three items, the third of which twists the meaning of the list in a humorous way (in this example, the double meaning of the word call is twisted). Other examples include sitcoms lines like:

Character: Can I get you something from the store? Advil, water, a new boyfriend?