Has anyone experienced respiratory failure with their loved one?

Two weeks ago, when the hospice nurse was checking on Mom, I asked her about Mom's breathing. At the time, she seemed to be breathing heavy (she was sleeping). The nurse said she had some apnea going on. That is the first time I noticed it. She would stop breathing for about 10-15 seconds. The nurse said she was sleeping (not unusual), but if she did it when she was awake, that could be a sign of respiratory failure.

Today, when Mom was sitting in her chair, I saw Mom's chest stop moving for about 9 seconds and then she started breathing a little faster and heavy. She was awake. The other thing that happened today, when we were coming back from the store, was that she started snoring. She was awake then, too. I seem to think both things are related.

I will call the nurse in the morning, but could it be the beginning of respiratory failure?? Has anyone experienced this?