Did I fail my patient?

I worked at a long term care facility as an agency nurse. It was a crazy night, I sent several patients to the hospital and so forth. A high fall risk patient managed to get out of bed into her wheelchair. She's pretty heavy and hard to transfer. I go into the room to give meds, and the CNA is frustrated due to her having had gotten out of bed alone. She was literally almost in tears from being in physical pain from the workload that night, and I felt so bad because she's an awesome worker. I of course jump in and help. During us transferring the patient, I remember thinking to myself that she could be a bit more gentle with the patient. However, I didn't deem her actions in my mind as abusive or anything, otherwise I would have said stopped her, and reported the behavior. So after this, I didn't really think much else of it.

A few days later, I get a call from the DON asking about said patient. Immediately in my head I thought the patient had complained about some meds that were out of stock that she was upset with me about that night, so I explained this to the DON.

The DON then goes on to ask me if I witnessed the CNA being rough with the patient. I stated that both the CNA and the patient were frustrated about the difficult transfer, but that I don't remember the CNA being rough.  It is the honest to God truth. Again, it was such a hectic night, I can't even remember what exactly the CNA did that made me feel she could be more gentle. I just remember us both having a tough time with transferring the patient. The DON let me know that I had not done anything wrong, but the patient had complained that the CNA was rough with her.

I take my job and my duty to protect my patients very seriously. I know that I would have intervened in and  reported any behavior from the CNA that I felt was abusive or aggressive. The last thing I want to do is make a comment insinuating that the CNA was abusive when I don't even remember the entire encounter. My main priority is to be an advocate for my patients, but I also don't want to potentially cost someone their license, and possibly even their freedom over a speculation.

Did I handle this situation right?

Nurses, would you do anything differently? If so, what?

I just don't want to feel like I failed my patient.