Guys, why st-stutter?

In my friendship with this guy, he's never brought up any other female friend/interest he may have had as we've gotten to know each other over the years. The other night we were on the phone for 5+hrs talking. At one point he said he replied to a female acquaintance in this FB group he's part of. As soon as he brought her up, he hesitated to continue explaining who she was and that she was an acquaintance, and stuttered over his words. He never stutters when he talks, and I've read that people will sometimes stutter if they get nervous.

Do you think he hesitated sharing about her with me because he may be interested in her?
(He did say that she told him she is highly sensitive and struggles with emotional immaturity.)
Guys, why st-stutter?
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