Pip can feel the hair standing up on the back of his neck, something deep inside of himself sending a warning. This all just doesn't quite add up. Pip casts his eyes to the ground in order to focus his thoughts. What did they know? He quietly mutters as he lists the information to himself:

One... The mayor made no mention of a plague. Such a detail would certainly be relevant given the other information he had shared.
Two... The number of open graves implies a much larger number of living yet infected townsfolk.
Three... A large portion of the town was in attendance at the performance the previous night with no signs of disease apparent.
Therefore... There is no plague here, not one on a large scale at least, these men are lying to us! Now what's the reason behind their deceit?
Four... They have many graves open at once, but there are no visible bodies waiting to be entombed, no forms wrapped in old cloth.
Five... They don't want us to come any closer to them and/or the graves.
Six... Cubby had smelled rotting flesh around the back fence while these fresh graves are much closer to the front and would have been apparent to him without having to enter the graveyard.
Conclusion... The men are either grave robbing, or hiding something in the graves. More likely robbing since they would probably fill them as they went if they were hiding things inside.

I think they're grave robbers! Pip quietly hisses to those standing next to him.