I highly doubt the crack is anything to worry about. If you have a poured concrete foundation especially, Surface cracks happen, but they by no means are a suggestion of an inferior foundation. I would be willing to bet there is either a step in the wall, or a window right near this crack isn't there?
Anything 1/8" of wider is a significant crack, also- does it go all the way thru? What does it look like on the exterior of the building? Can you see it or is it covered up?
I assume water comes in it when the groundwater is high?
Bottom line is- take a bunch of pics of it, and then you should try to get it fixed sooner than later. Fixing it will only cost about $900 or so- to get a professional to go in there with an ultra-strong epoxy injection that is actually stronger than the concrete itself. (Hire someone that this stuff is ALL they do...)
If you need any further help or thoughts, please let me know. Thanks,
In my limited experience a horizontal crack tends to be more serious and of concern than a vertical type of crack. let me know and I know a local Structural engineer or just google someone. Tim Dolan.