This is not unusual regardless of circumstances. Most landlords nowadays use software that generates prices based on lease terms. A lease for six months is less desirable than for 12 months because there is always a gap in tenancy, necessity for renovation between tenants, etc.

This causes weird outcomes depending on the lease length, like 13 months being significantly cheaper per month than 12, or one month (if you needed some extra time before your next place opens up) being three times the cost per month as compared to a standard lease.