Audi running hot? Had coolant flushed?

My 98 Audi started running a little hot for a couple days, i went and had the coolant flushed on friday. The people at Jiffy Lube didn't let my car run long enough, so when i left the shop steam started spewing out from under my hood. It was all antifreeze. I got it home and let it cool down, We checked the level, and the antifreeze was at minimum. So we brought the levels back up. On Saturday i drove it back to Jiffy Lube, and of course they were no help. He told me that i'm supposed to bring it back in 48 hours after service. And that the steam was from trapped air bubbles. Still, my car is running hotter than usual. My temp gauge has always been directly in the center since i bought it, now it's just right above the center line, not hitting the next little notch..and it doesn't continue rising, it stays right at that spot. Obviously, when i run my heater everything balances back out. My car hasn't steamed up since the initial first time. What are my next options? Check the thermostat? If they flushed my coolant wouldn't that have pushed stuff through so there wouldn't be a blockage in the radiator? Would getting a simple oil change help?