Yep. That was an act of bad faith on his part. Courts take a very dim view of that especially when you then try to seek relief.
There was a similar case I learned about in law school. Same deal with a big plot of land subdivided up into individual plots. Well it turns out the developer was one lot off on the plot map. So years later, every home owner discovered that they did not own their home but instead owned their next door neighbor's house.
Some greedy bastard then realized that his next door neighbor's house was actually a lot more valuable than his so he tried to sue to get it. The judge ruled that no, everybody bought their homes having seen them and the lot they were on or having had them built on the lot they were on so everybody actually owned the house they were in and not their neighbor's...even though technically they should have. He "quieted" title. That was by far the most equitable thing to do and I agree with his ruling.
"Saw construction going on..."
"Honest, Your Honor! Sure, I was a little puzzled for a moment, but then I just assumed that I must be mistaken. It was late at night, and raining heavily, my glasses were broken, and I had a stye in my left eye."
Unless the Plaintiff acted in a ridiculous fashion, ostentatiously taking photographs, hitting the bars afterwards and bragging to everyone about the "big windfall" coming his way, it's impossible to prove - and he is under absolutely no obligation to "follow up" on any slight suspicion that might have momentarily crossed his mind.
Regards,