I picked up my Model X at the end of December 2016, and since then I've had to take it back to the SC in Costa Mesa a few times, too. I'm trying to be just as patient as you have been. My problems are:
1) Sudden glass shattering of quarter window on driver's side falcon wing door. (This happened on New Year's Day Sunday after I've had the car for just over a week.) The SC later told me it was mounted wrong. It was in the SC for over a week, but i had to drive with the shattered window for a week until I was able to secure an appointment with the SCt.
2) 2nd row driver's side seat started making a creaking sound and would not recline anymore. SC later said it was a manufacturing problem and so the warranty kicked in for them to fix that.
3) After we finally picked up the car from the SC, a few days later while driving on the freeway, the tire pressure alert suddenly came on, and by the time I was able to pull over at a freeway exit, the passenger rear tire was completely damaged. 24-hour roadside assistance was called, and within an hour, someone came with a loaner tire. Tesla doesn't warranty any of its tires, so I ended up getting it replaced at America's Tires and paying hundreds of dollars to warranty all the tires through America's Tires. And my wife who took it in forgot to ask the America's Tires folks to find out what caused the damage to the itre, so we will never know though in the back of my mind I believe it was a bad tire to start with.
4) This coming Monday, we finally got an appointment (it was pushed back because the SC supposedly experienced a power outage a few days before our appointment). So I'm taking it in again because my wife and I noticed the large windows on each falcon wing door isn't put in the same way--the trimmings are off, and my kids complained about being able to hear the air coming through the driver's side falcon wing door. Our Auto Steer isn't working at all unless we're stuck in traffic on the carpool lane of the Orange Crush. The garage door doesn't automatically close when I'm using my FOB, but it does automatically close when my wife uses her FOB. (the SC had a ranger come out to take a look at it, and he didn't even know what to do and had to call someone; eventually, he told my wife the Model X had to be "locked" using my FOB before it can work; though it worked, it never worked again for me when I tried it when I came home--my wife never told the ranger that it works fine when she uses her FOB). A few weeks back the dashboard had a yellow Call Tesla Service warning. And the list goes on.
I'm thinking my X could be a lemon, too.
At least we got an X loaner car last time when we brought it in to the SC. Did you get one when yours was in the SC in Costa Mesa?