It's a magical world

I think it depends on how you were/are using that particular email address--if it's something you use on a fair number of sites, odds are good that it's been exposed at one point or another. Have I Been Pwned? is the service to check. If you were using an address that you wanted to keep secret for whatever reason, or not have associated with that LJ info publicly, you might consider getting another email address and using that with whatever accounts/services you wanted to be less widely known. For me, I have a fandom email that I have attached to most of my fannish accounts; I use it as an alias of my main email account--and I've just checked and seen that it's been exposed in two different breaches. It's a good idea to run your email(s) through HIBP, review your third-party app or device authorizations, and change your email address password from time to time. But in principle if you're using unique passwords for everything changing your account email shouldn't be necessary.