OK, so do I have a problem?
My 12V interior lights dim, slightly, for a while. (I suppose I could say that they brighten, slightly, for a while, now and then.) They stay dimmer for a few minutes to an hour or so, and then brighten back up. The dimming is not severe - in fact, sometimes I only notice that they are a bit dimmer, without having noticed when they did that. All of the lights do this in unison. I am not aware of any other symptoms.
I have 50 amp park service, and I am using it almost to the hilt. I have 2 heaters running. I have no 120v lights, no TV working. The fridge is on Auto, which means it is using 120 for heating the refrigerant. I am using my laptop, plugged into 120. I am not using 120, internally, for anything else.
I have an AC Line Meter plugged in, in the bathroom. It reads anywhere from 114v to 116v, and does not vary with the dimming of the 12v lights. I do have a microwave, but I use it for a few minutes a day and it does not seem to affect the lights.
I am using 12v lighting, as needed. I'm not using 12v for anything else that is voluntary. Of course, the fridge has a circuit board that is using 12v, but I wouldn't think a lot of it - and I don't get into the fridge, often. I suppose there are other circuit boards being powered by 12v. I suppose the furnace is controlled by a 12v board, but the lights do not react in time with the furnace. (It's not running, very often.)
So should I worry, or quit worrying?