Fraud?

Hi, I live in Arkansas..I was going over my wifes divorce papers recently and noticed something peculiar..

In her settlement with her ex she was supposed to get a house and lot which at that point in time was owned by his mom and he would retain the marital house. We found out that his family(his mom was quite incapable of this kind of shrewdness) had sliced off a 80x125 section of the lot that my wife was supposed to get(house and lot are not described in divorce agreement but it implies the house and the property it sits on etc)..Anyway the reason we discovered this is we tried to pay taxes and the tax office told us they had not yet gotten the final paperwork on the division..what? This was about 5 months after the divorce was finalized..so we figured we couldnt do anything about it(almost 3 years ago now)..Well recently I was looking at the papers and noticed that the dates dont match up..The divorce was finalized on the May 5th and the paperwork on the lot was finalized on the May 7th(my wife had no idea this was taking place and was told by her ex's attorney that everything was in order so she did not have to go to court) These documents were sent to her a couple of weeks or so after the finalization date..

I guess I am just doubting my own assessment of the situation..this looks like intrinsic fraud or fraud to me? anyone else..at the least I would think that the survey in power at the time of divorce being filed with the court would be the one to look at?..this would include the 80x125 lot!! (btw:the divorce agreement was signed by both parties in February and the paperwork I've gotten shows the lot paperwork was done in April-May) How would we go about clarifying this with the courts or should we just forget it..the lot is worth about $800-1000(but cuts our property value down probably 5-7k) ..Any comments or suggestions would be interesting..I would not mind paying a filing fee if that would get the ball rolling to put this info in front of a judge...