I think some people (maybe even most) mean they literally found it arousing, but I do think it has become such a stock response that it doesn't necessarily mean arousal at all, but just "this was really good". Like, when people say LOL they usually aren't literally laughing out loud. Just amused.

idk. I don't say things like "I'll be in my bunk" but I do say things like "that was hot" without meaning I found it arousing.