I hope you checked your purchase paperwork closely, because a closing can be quite hectic and people get impatient if you insist on reading absolutely everything like I did. They could easily pass a disclosure statement by you to be signed if you aren’t careful. That said…
That should have been disclosed before the sale. I would guess that you could sue the seller. I would get on top of this because you probably have no idea of what the easement entails, whether it is exclusive rights to cross the property, they may be able to add as many lines as they desire in the future or add surface appurtenances. I think it would have had a direct effect if known on the market value of the property. I think this is very serious and if they used a real estate agent that they could be in trouble also. I don’t know how long ago this was but I wouldn’t delay as it could be a time sensitive issue. Good luck.