When's the last time it was done?
High mileage transmission service usually only offers problems if the service hasn't been done or has been excessively long since it has been done, the reason being that sludge will form around the seals. As the seals wear, the sludge keeps leaks from forming, but when you change the fluid, the detergents in the new batch will deteriorate the sludge build-up and leaks will develop -IF- the seals were going bad to begin with.
I change my 1999's fluid and filter around 10-15k because I do loads of city driving here in Atlanta, but I think the recommended service is like 20-30k now.