As a former techie, I suspect the system admins needed to test some functionality of the MF website and particularly the shop listing or testing functions. They had a couple of options for doing the testing, do the test while the site is live with the disclaimer you saw, or take the site offline to do the testing. There are pros and cons to each option, but it appears they chose to test while the site was live.
Some companies take their website offline every night to do updates, patches, or testing (STN comes to mind). Most companies probably don't have such a structured maintenance schedule.
Just my two lincolns......
"We're just two lost souls swimming in a fish bowl -- year after year..."