I have recently been in contact with the marine biology dept. of the Dallas Aquarium. Jeff was kind enough to answer some questions I had regaurding the indentification of a gulf anemone. He expressed a differnet view point than what is usully heard about keeping multiple anemones in one tank. I have copied the email as I find the information very plausable.....
I think the heat is definitely playing a role in the lack of tentacle expansion with these anemones. Any severe temperature swings, especially those that last for extended periods of time, will undoubtedly cause at very least some discomfort to any aquatic life and especially in sessile invertebrates. I would definitely "force" myself back down to the coast to take a look. I would bet there would be a noticeable difference in tentacle appearance after the temps have been back down to normal for a few weeks.
Anemones will naturally live in clusters. A few peeks at some of the more dominate reefs of the world will show many anemones, especially pacific varieties living in very close proximity and often time touching each other. In an aquarium setting, I wouldn't worry about alleopathy (chemical warfare) between the anemones. This is a much more common occurrence with soft corals (Cladiella sp, sarcophtyon sp, etc). These soft corals lack the powerful nematocysts (stinging cells usually used in prey capture) of anemones, so they will release terpines into the water to injure or kill other corals competing for space. Anyway, back to the anemones. As long as they are the same species, the nematocysts will not recognize the each other and will not fire; therefore being able to live in very close proximity without any issues. There is a very interesting theory closely tied to this with the Clownfish/anemone relationship, but thats something for a different time. Now, if the anemones were of different species there would be a major "war" going on between the two, but it would be all physical response passed through the nematocysts of the differing species of anemones causing them to sting (in a predator/prey response) repeatedly until one of them moves or dies.
Hopefully this helps answer your questions. If you have any further questions, feel free to contact me. I will do my best to answer them for you.
The Dallas World Aquarium
(214)720-2224 x 318