Phoenix area - east valley. I've had this palm for about 1 year, planted in May 2020. It has been looking great until the past week. It is in sandy, fast draining but poor soil, and full sun except for the last 2 hours of the day. It was watered 1x per week over last summer, then tapered off to no water all winter. Resumed 1x per month in early April, now back to 1x per week since it is getting hot again (105 yesterday) and fronds have started drooping in between waterings. I fertilized it with palm fertilizer in early May.

The newest full leaf is all green but the others have started to yellow from the centers outward. There are no spots, just yellowing.

Should I be concerned? What might be causing this?