Do you think that's a lot of loss for an air pocket?

 

Cant say. I am not sure what 20 some ounces looks to be. I know in the past, once just recently, the first time took about 1/3 of the jug. The second fill up was just about 1/4. The next 2 times were just a few splashes. Havent had a problem since then.
Im not saying thats exactly what it is in yours, but I have a pretty good feeling that should solve it if your pressure test comes back fine.

 

Well there's about 128 oz in a coolant jug. So 28 oz is roughly 1/4 a jug.

 

Well definitely hit the compression test. Better safe than sorry. For all you know they forgot a bolt and its squeezing through the tiniest space under pressure. If it comes back fine, then its most likely you just need to fill her up a couple days. and 1/4 of a jug isnt out of the ordinary unless it needs a 1/4 of a jug for 3 days+. then you have a problem.

 

Finally got around to driving car and this time I lost 3.5 oz of coolant which isn't even half a cup. I could see it in the radiator. Hopefully it was just air pockets. Haven't been able to take it back for the pressure test. Dealt with the battery stuff then my oldest son had his 3 yr old cat to unexpectantly die on his bed at 3:30 a.m. this morning. Add to that, my middle son got his enlistment done and had a ship date of 8/27 to get moved up to 7/22 and will be gone 6 months. This mother has had enough stress already.