The service guys are loath to add too much oil for fear of overfilling. The same thing happened to me after my 1200 mile service. Perform the oil service, then the new oil filter absorbs about a quart over the first several miles you drive, requiring you to top it up. My tech made it up to me by giving me an oil kit that lives in my trunk. It contains a quart of oil, a funnel and some other goodies, all in a handsome BMW-branded zippered pouch. The pouch has velcro on the back so it can be affixed to one of the sidewalls in my trunk.
And -- FYI: Engine Oil capacity with filter is 9.3 quarts; without filter it's 8.9 quarts. Covered extensively here: