Should there be any follow up with sleep doc/clinic?

I was diagnosed about 2 years ago with both OSA and central apneas, about half and half. I was quite surprised, as I had none of the normal symptoms. The sleep study came after several months of trying to figure out the cause of PVCs, premature ventricular contractions. My apnea is mild, but still 50-80 per night---yikes. I started treatment immediately, adjusted to it very easily and always use my machine. The PVCs went away, and there was a near instant improvement in my concentration. I was back to reading a book a week, something I had not been able to do for some time. And dreams came back. . .could not say how long it had been since I had dreamed.

Right now my 30 day average AHI is .5, total AI is .4 and central AI is .3. All good, but there can be days when apneas go back to 4-6 per hour, which is still lower than my tests showed. I wonder why this happens, but when I call the clinic, they check my numbers, say things look great, no reason for concern. Another thing that happens is a zero reading after 4-6 hours of sleep, then I get up for a bathroom break, and the AHI can be 3 or 4 events per hour for the night, meaning 20-30 events (total hours of sleep x # per hour) in the last hour of sleep.

So, should there be follow up visits so I can get some answers? Can anyone explain why there are spikes in apneas, that come in clusters, 2-3 in a week, then back to my normal, less than 1 per hour, for weeks at a time?

The most obvious explanation would be position-related obstruction. Occasionally you lie an position which makes your obstruction worse causing a temporary increase in your AHI. Doesn't sound like a bit problem, but if you are worried you cold see about increasing your pressure a little to see if it resolves.