Ah, I don't read too much into it. The lady did help to raise him, after all.... You or I might do the same.
But if he's really so cynical as to have a "campaign reason" for this, I can think of two.
1. Playing for sympathy -- he's "humanizing" himself.
2. He'll be visiting friends whom he's afraid will talk.
Thanks for the comments. Your take on it is reasoned. We’ll see.