I had my local garage do my oil change this time as opposed to my dealer. I inspected all the plastic retainers and sure enough 3 were missing. These do not or cannot pop out on their own. Definitely my dealer who lost/forgot to put them back in.Good news is he had retainers so we replaced the missing ones. I suggest buying a bag full of these on ebay for dirt cheap and keeping them in the trunk. After removal the end that gets inserted into the hole is rather splayed apart and takes some coaxing to get back in, most likely why they omitted a few at the dealership. Here is what you need. http://www.ebay.com/itm/371222529360?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT
This is yet another example of how easy it is to screw up oil/filter changes on Hyundai's -- Surprised they would use these flimsy plastic clips in a rather important area. And, of course, it doesn't help when they're working on someone else's car and don't really care all that much.