Depends on how you look at it. If you are thinking the life span of the fish, possibly. The fish she has will be fine in there for now and thrive with proper filter maint and water changes.
Why is it everyone has to hammer people that have goldfish/fish that get large with "OMG!!! You need this size tank, blah blah blah" let them enjoy their fish..
They sure aint gunna get full sized over night, or in a yr..
LBF - I have an above ground pound in my back yard with 6 10" Koi ( there is no s on the end singular and plural are spelled Koi, just like Deer) 3 4" comets, 2 common Plecos and a breeding pair of Jewels, the koi have been in there 2 yrs. By your thoughts I should have them in a 20,000 gallon pond. They are fine, they are healthy....