Air in oil damper of suspension fork after pulling hard while disassembling
I do not have experience with the Reba, but Boxxers and Lyriks. Separating the casting from the stanchions should not be that hard. It is important that the shaft where the bottom screws are screwed in can move easily and the air can pass before you try to separate the parts. You have loosen the screws a couple of turns like it's suggested in the manual. Then you have struck the screws. That does not have to be that gentle. If one or both screws cannot be easily moved up and down slightly repeat this task by loosing the screws a couple of more turns and striking on the screws again.

In the manual it looks like it's an open bath damping, so air is in the oil chamber by design. You cannot have put more air in it by pulling the fork apart. 

If the sealing between the damper chamber and the lower leg is worn out there could be that oil is lost. But this should not occur with a newer fork. And then there should have been more oil in the lower leg. To make sure you could measure the oil level. Either per oil height (but I'm not sure how accurate this is) or by removing all the oil and adding oil back - preferable by cleaning everything and using new oil. Don't remove the old oil if you do not have the right spare oil.