Tense change in first person

Sounds right to me, assuming it's someone else besides the narrator who is clinking the ice. Large gatherings make me twitchy is just like I have brown hair; it's a present condition.

You could say, Large gatherings made me twitchy, if she's going to change later, say. Or if you preferred it for whatever reason. But the present tense is perfectly fine.

If I may add a bit of grammatical nerd-precision here: The sentence isn't a problem because it's understood to be in the habitual aspect. That is, the narrator is saying, "As a rule, large gatherings make me twitchy," not "Right now, as I'm writing this, some large gatherings have entered the room and are causing me to twitch."

Another simple example, borrowing your starting point: She swirled her drink around, tossing a coy smile at some handsome doctor type. I could tell from the look that she was already in mid-seduction. Some things never change. Again, the last sentence is in a different tense, but we understand that it's obviously meant as a statement of general truth.

I think it sounds great I'm glad you posted this because I had the same question.