Juvanile Iguana acting up?

My firend has a Juvanile green iguana, he has had it for about 2 months. Before it had been a wonderfully behaved little critter. we then went and got her a larger aqaurium 80 gallons. since then she has just been skittsh and tail whips and occasionally tries to bite. she pretty much does everything to avoid being handled. we have her on the proper diet and she is healthy. the only thing i can see my firend doing wrong is that while handling her, by the time she calms down her puts her back in her cage. does anyone have a reasoning why she freaks out so much even though she used to be so well behaved.