Seller did not transfer "last month rent" on sale

[Jake Sablosky]

Hey there BP,

So unfortunately I did not do my due diligence correctly during the purchase of a property in October 2019. The seller's lease states that she collected first and last month's rent, AND a security deposit. Upon sale, she only transferred the security deposit to me (as well as rent for the remaining days in October - prorated). 

Am I screwed? Or can I go back to the seller and legally ask for each tenant's last month's rent? (Because the tenants don't want to pay it).