Cat meowes at other cat
I have two cats, both of them are about 8 year old neutered, male adults. I've had one since he was a kitten, and I adopted the other one about 8 months ago. Since the cats didn't get along (I've followed all the guidelines about taking it slow etc.) we've kept them in seperate rooms for a long time. Now we installed 2 meshed doors, one on each room, with hallway separating the two(about 4 meters apart). The first time they saw eachother through the meshed doors, there wasn't any hissing or growing, no sounds, but they were looking at eachother intensly. Overall I think it went good. We've repeated the meetings several times, maybe 10 times. Now, we've shortened the distance between the two doors and now the doors are about a meter apart, but not facing eachother, but at a 90 degree angle (hopefully this is understandable. Imagine two rooms, you go out through one, and turn right to enter the other room after one meter). They've seen each other about 5 times like this so far, and there were no sounds, only intense looks which I managed to break up by distracting them.
To the point: on the 6th and 7th meeting on 1 m apart, the newly adopted cat meowed at the 'old' cat on first seeing him after opening the doors. The meow wasn't loud and didn't seem really aggressive, but I'm conserned that maybe it will lead to a verbal fight in the future. The other cat didn't really react to his meow, because I also distracted him(the old cat was the more aggressive one in the past).
Do you have any ideas what this meowing would mean?
The old cat walks around the room in between looking at the newcomer, while the newcomer just lays there and keeps looking at the other one.
Am I heading in the right direction? Am I doing things too fast?