I am NO expert on the subject. That being said I've heard that most tenor ukes tuned to low"g" tend to have a saddle made on a slant to compensate for string tensions - I'm not sure if that's true - I've never actually played or even seen anything other than a soprano in person, so my advice is useless there. if your intonation is prettymuch bang on, except for the "a" string being a little off, maybe you should leave it be. If it doesn't really bug you, why fix it? But of course, if it does bug you, maybe you should consider taking it in to get fixed (not the same way you would get a dog fixed mind you, different principles), if it were a cheapie, which it doesn't look like it is, then I'd say you could fix it yourself. It doesn't look like it though, so unless you have some good experience with that sort of thing, take it into a luthier, or if that was a custom one, to whoever built it.
edit: I think the best thing you can do at the moment is just keep playing, don't think about it, if you can't really notice it, is anything really wrong? I mean, I don't want to say that you should play a "broken" or "bad" instrument, but I think a rash decision could just make things worse, sometimes we chase after "perfection" so adamantly that what ends up happening could actually be harmful. So play it for a few weeks, maybe even a few months, if it doesn't bother you, why mess with a good thing?