I have a 2015 Model S 70 which I bought used about 6 months ago and about 67k miles. It has had one or two issues that resulted in the digital aspects shutting down and visits to the service center, including replacement of a "daughter board". One of the symptoms that led up to this was that charging was starting and stopping in my garage somewhat frequently. Over the last couple of months, I haven't had such severe issues, and the worst seems to have been one or two screen resets needed.
However, once in awhile the charging will start and stop a bit more than I expect in the garage. Last night, for example, my phone told me of two or three points when it just started and stopped maybe a bit later. It's been a bit cold here (in the 20s at night) so maybe that is somewhat related? I don't think any miles are being added. If I happen to catch the vehicle doing this sort of thing during the day, I have once or twice simply unplugged it, just on general suspicion that it shouldn't be doing that too much.
So I thought I'd ask a question of fellow drivers as to how often they expect the vehicle to start and stop charging when it is just sitting plugged in. My charges station is an old Clipper Creek CS-40 (about 7 kW) that has powered a Leaf and then a Volt since 2013, without incident, once I got something worked out on the initial install.