People sell for all sorts of reasons, loss of job, job relocation, etc. If there was an issue with the entire complex, you would see more than one unit on the market at this time. Glad to see you are paying attention, but I wouldn't be concerned that there is some underlying major problem. Obviously I, nor anyone in their right mind is going make any sort of guarantee that there are no problems, but considering the low turn over rate (3 Sales in the past and1 Active listing) I wouldn't read too much into it other than the current owners personal situation has changed since purchasing the property.
It's a nice unit, let me know if you would like to check it out at your earliest convenience.