If a guy suddenly talk to me in a cutesy voice?

Background: have a somewhat young-sounding voice and due to the way I pronounce, I have been told by quite a few people that I sound cute.

One day, I was greeting "Morning" to my part time job boss (31 year old) who knows I like him, and is trying to keep his distance from me. Suddenly, he replied "Morning" in a cutesy way that was totally unexpected, unheard of and unlike him.

In fact, he was taken aback by it too and quickly repeated in a his usual normal tone.

What could be the reason for his sudden behaviour?

If a guy suddenly talk to me in a cutesy voice?
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