You are free, and no one is against you changing your password because, as you indicated, it is for security reasons.
But what reason would that be that you resort to changing passwords? I mean, you can just tick the Always Logged In in your browser so you don't have to relog. I don't know of any reason that someone will hack your forum account even if it makes a lot of money from signature campaigns, you can always report that you're account's stolen.
When an account activates and appears suspicious, or the manner of posting and interactions in the account changes, reputable forum users usually use the password changing time as evidence to show the user wrong or to protect the account from being utilised by a hacker.
Highly circumstantial evidence though, what if they've forgotten their password or they've updated their password scheme but that's an unlikely thing to happen. Most password changes are almost always suspicious given how account selling is a thing here. Nothing wrong with changing password, as long as you can prove it's you by signing your PGP key, this one pretty much helps you avoid the suspicion altogether.