Patient Independent or not?

I recently treated a 72 year old lady who had dynamic hip screw done on her (L) hip post-fractured NOF from a mechanical fall. She was then transferred to rehab ward under the DRAC team. During the first session, I progressed her ambulation with a gutter frame to a wheel Zimmer frame. While using a WZF for the first time, the patient was ambulating slow but considerably steady. And before writing her notes, I noticed that she was ambulating with WZF to the toilet without supervision and she told me that she had been to the toilet with the frame four times by herself. I also felt that the patient was safe using the frame so I stated in the medical notes that she was independent mobilizing with a WZF. On the next day, I found out the patient had a fall in the middle of the night while mobilising to the toilet, resulting in severe hip pain and was awaiting for bone scan. My supervisor asked me if I thought the patient was safe ambulating with a WZF and I supported myself with the fact that the patient was ambulating independently to the toilet four times during the day. My supervisor then said even though the patient felt safe, I should have written in the notes that standby assist was required as it was her first day using a WZF in order to protect ourselves from being blamed for accident. On reflection, even though the patient was blamed for not calling the nurse at midnight, just to be on the safe side, I should probably have given the patient more sessions to practice walking with a frame despite the patient appeared to be safe and independent before stating the patient was independent mobilising with WZF in the medical notes.