hi, hope someone can advise

i have a small (30" tall) olive tree in a ceramic tub, which over the summer
was very healthy. it's been in the conservatory since about the last week
of november. just before xmas, it started to shed its leaves, which had
gone brown and curled. thinking that there might be something about its
location that was causing stress, i moved it to near the front door. since
it has been there, new pale green growth has appeared all over the plant,
while the older growth continues to shrivel and drop. is this normal for an
olive? or should i take some action? i have been watering very sparingly
about once a week. very grateful for any tips, pointers, urls etc.