As long as the rest of the plant including the root system are ok then yes it is just a case of the plant needing more water. I would imagine that one gallon container drains quite fast. Citrus trees actually like to dry out a little bit between waterings but if it's wilting I think it is just getting too dry in between.

too dry. they thrive in hot sun as long as they have enough water. too wet for too long and they rot, too dry and they dehydrate.

Let's remember that when plants are grown in containers, conditions that are too wet OR too dry will cause the leaves to wilt.

The primary 2reason is lack of adequate moisture being transported throughout the vascular system. The underlying cause might be that there is insufficient available moisture. But it might also be caused by the death of much of the absorbing root hairs due to excessive water retention or over watering.

Wr want the water to drain rapidly, but it first must fill the whole soil volume. Container size doesn't have much to do with it.