No problem at that size. If it is the species that gets larger, then as it grows larger it can be problamatic.
Have you not added anything in three years? I got a similiar hitch hiker I attributed from adding macro. Was the only thing added in a years time. I moved it to the sump, where it has grown even larger. Fun little guys though, I have one in my reefs sump as well that was also a freebee.