Really?! Because I swore I actually remember this one episode where she moves in with the boys and I didn't see her with glasses! Of course that may have been my stupid fits of forgetting stuff. Man, I feel so dumb XD!
That's "Vinny's Visit" and she doesn't move in with them, she visits them. She wears her glasses during the majority of the episode, occasionally placing them on the top of her head like she did in A Chipmunk Reunion.