I can personally say that she does have aspergers to some degree (I can attest to that since I am affected myself). She has a mostly emotionless face; that is a big part. I get expressive sometimes, but I mostly have an emotionless default (you could say I look like Data (Star Trek TNG), Lurch (Addams Family) or Edward (Edward Scissorhands).
There are some other things to which Maud has that hint that she is affected with this mild form of Autism. Her intense interest and remarkable head for geology is very similar to other people that are on the spectrum. I just so happen to have a life long love of trains and railroads (I now also like other types of transportation too). A friend of mine at school, who also is affected, has an obsession with video game systems, computers, and fictional universes. There are many others.
Finally on a more serious note. People on the spectrum appear to act or be more mature, calm, or reserved than most neuotypical people around them. Maud is like this a lot in the series (while most of the characters are over the top as well as hyper, Maud is a calmer and more reserved type). I am like this too, while most people at the school that I go to are what you'd expect high school teenagers to act like, I and a few other people like me act more like soldiers, businessmen, or adults.
In conclusion I can safely say that Maud is very much a person (or pony, depending on which version you like more) that is affected by aspergers syndrome. This is not coming from an outsider, I too am a person that is affected by aspergers. This analysis is 100% accurate as far as my experience has given me knowledge.