Seller Renewing a Lease After Property is Under Contract

[Nate LaBlance]

Hey all, I recently purchased my first owner occupied duplex and inherited the tenants the other side. Once I put the property under contract I was given a copy of the inherited tenant's current lease, which was due to end a month after I closed. Come to find out, about a week after the property was put under contract, the seller renewed that tenant's lease for another year (when the current lease wasn't due to end for another 3 months and 20 days). Is this legal to renew/extend the lease of a tenant after the property has been put under contract? And, without disclosing that information to the buyer?

I found out about the lease renewal from MY TENANT when I notified them that their lease term was coming to an end. So not only do I look unprofessional in my first interaction with my new tenant, but I'm also stuck with the terms of some one elses lease not just for the one month as I had planned, but for another 12 months. 

Is there any action I can take here, or do I simply chalk it up to a learning lesson and don't let it happen again? Any advice is much appreciated!