You said..."Maybe I wasn't too clear as of describing what my male montium did. He "jerked his head" as if he was trying to get a female to notice him"....you were clear, but sometimes the head jerking is expressing annoyance or being upset with a situation (pre-aggressive/defence behaviour, if you will). I have seen several of my male montane chameleons do this head jerking when they are upset/annoyed/confused by something. If pushed, the behavior would soon change to aggressive behavior.
Also...in my email to you, I said that a chameleon seeing a chameleon of another species could react to that chameleon as if it were something to mate with (thus acknowledging that the jerking might also be a "mating call"
. To be more clear, when two chameleons of different species meet they don't always recognize the sex of each other. If they would never meet in the wild (because they lived in different areas) they wouldn't be able to recognize each other but might recognize that the other one was not a male of its own species and thus not something to be aggressive with.
When chameleons are first placed together in a cage you may see very little reaction from them. The first reaction of some might be like "Am I going to get eaten? Should I run? Should I stay still? Is the "intruder" something that I should just ignore?" so the chameleon may not react at all. It has been well documented that a chameleon introduced to the cage of another won't always display aggression/mating reactions to the intruding chameleon at first. I have seen one suddenly "wake up" to the fact that an "intruder" is there and literally drop dead from what I can only assume is sudden terror.
You said..."Furthermore, my panthers didn't have a respond to his action, they simply continue doing their own thing as if he wasn't there and therefore, there's no stress factor involve"...stress in chameleons is often silent. You can't SEE changes in their adrenal glands; you can't see changes in their immune system right away. While short infrequent encounters with stress will have little affect on your chameleon, if your chameleon is stressed too often (like being in sight of another chameleon in the next cage where there is no visual barrier), he will sooner or later exhibit health issues.
Whether the head jerking was a "mating call" or not is not the prime concern here. Whether your chameleon is "gay" or not is not a prime concern. The health and welfare of your chameleons is more important.