I was thinking she was doing a quick job for somepony, sort of "I'm busy mind if you bring this package to Canterlot? I'll pay for your train fare" type of thing. While she would originally stick around because of safety in numbers, she warms up to others quickly when they prove they deserve it, and after that friends are more valuable a commodity than food on the streets or anywhere else, and she's protective of them.
That sounds fair.
As for knowing Diego, Grease wouldn't be the type to go on tours... Except on a family vacation or something of the sort. Though unless he really stood out I doubt she would remember him any more than vague recognition.