Form rejection or not?

I would say that it's a form, but perhaps a higher tier one that they send to writers whose work they enjoyed (I've never submitted to NANO, so maybe someone with experience with them can confirm). A personal rejection will usually have a line or two directly referencing your story and saying what the editor liked or didn't like about it.

^^What Sai said. I've gotten several rejections like that from agents, and even though they're still form rejections, it is nice to hear sometimes. You'll know when a rejection is personalized because it'll say something specific about your work and why the agent/editor is turning it down.

I don't know much about NANO either, but if they have a page on querytracker or some other site, you might want to visit it and see what kinds of responses others are getting.

according to the rejection wiki their standard says: "Thank you for sending us "TITLE". We appreciate the chance to read it. Unfortunately, the piece is not for us.
Thanks again. Best of luck placing this piece elsewhere." so I would say yours is definitely a higher tier. good job!