Rental Lease Question

[Ryan Cash]

I rented a place for two years.  We signed a lease the first year and the lease stated that after a year it could be renewed or you could go month to month with a 10% increase.  When the first year came up, my landlord did not approach me about a new lease or going month to month.  We continued to pay the same rate that we paid for the year long lease for the next 12.5 months with no issues.  We just moved out and now he is saying I owe him the 10% difference for each of the last 12 months because we went month to month for the last year.  Can he do this?  I would think it is the responsibility of the landlord to 1) communicate after a year lease has come up about renewing or going month to month 2) Correct me right away when I pay the same rate as we did when in our lease letting me know that I owe 10% more or need to sign another lease.  I live in Oregon.