I would say that is very likely an error on the site, if you notice in my screenshot above in post #17 Select has the same line below the price as well. You have never in the past that I can remember had to enter into a new contract to downgrade/upgrade a base package... Normally the "for 12 months with 24-MO. agreement" line is only shown on the package pricing page for new customers.
The very bottom of the screenshot says "New Customers"