Maybe. What sort of terrier?
There is absolutely no way for us to say. You haven't mentioned what sort of terrier or provided any sort of picture, the puppy is only 4 weeks and not all Chihuahuas ears will stand. The first link is the Chihuahua parent club and you can look up terrier breed clubs in the second link.
http://www.chihuahuaclubofamerica.com/ http://www.akc.org/breederinfo/breeder_search.cfm
q5762034.html#a2906893 http://www.wildheirlabradorrescue.org/readingroom/what-is-a-back-yard-breeder.php
http://members.tripod.com/antique_fcr/goodbreeder.html
http://www.wonderpuppy.net/1breeding.php
http://home.comcast.net/~NoPuppyMillsVA/Poo-dogs___Designer_Mutts/poo-dogs___designer_mutts.html
http://www.petfinder.com/index.html
http://www.chihuahuaclubofamerica.com/ http://www.akc.org/breederinfo/breeder_search.cfm
q5762034.html#a2906893 http://www.wildheirlabradorrescue.org/readingroom/what-is-a-back-yard-breeder.php
http://members.tripod.com/antique_fcr/goodbreeder.html
http://www.wonderpuppy.net/1breeding.php
http://home.comcast.net/~NoPuppyMillsVA/Poo-dogs___Designer_Mutts/poo-dogs___designer_mutts.html
http://www.petfinder.com/index.html