Not a glitch. Just something that shows the radio system in action
When you swapped from Socal to Pt Mugu, if you did indeed use 126.65 instead of 128.65, you were actually tuned to a LA Center frequency, with the transmitter being located on top of a mountain (Mt Laguna, just SE of the JLI VOR). The controller may not have caught this, depending on his workload (we get an alert when pilots change freqs so we can more easily wear multiple hats) and when you checked in calling Pt Mugu approach, he put on his Pt Mugu hat and responded. All is well, right? Does it really matter what freq you're on if it's really the same controller working both positions?
It very much does.
When you initially checked in with "Pt Mugu" (really, LAX Center at the Mt Laguna transmitter), you were at the outer range of the radio transmission/reception limits based on your altitude and the altitude of ATC's transmitter atop the mountain (I kid you not, we model all of that, down to the foot).
Once you exceeded 118.2nm from Mt Laguna, with you being level at 8000ft, it was all over and you lost comms. At that point, you would not have heard any more transmissions from ATC.
What should've happened is that when you checked in on the LAX Center freq, a bewildered center controller should've said, "go back to your previous frequency and ask for a new frequency," or perhaps, "say location..." followed by, "try Pt Mugu Approach 128.65, you're on 126.65." etc. However, that didn't happen, and the voice behind the mic responded as "Pt Mugu approach" so you had no reason to suspect an issue.
In the future, you'll hear ATC's transmissions becoming distorted and mixed with static as you approach the reception limits, that will be a clue that it's time to ask for a new freq (this happens in real life quite frequently out in the boonies).
The only thing you could've done differently, Steve, was try going back to the previous freq once you realized you lost comms (not always possible if you've already erased the previous freq, which is reasonable if you've established comms with the new controller), OR try looking up an approach frequency for the 'local' area, ie, the nearest airport with an instrument approach, pull up any of the approach plates (such as OXR, CMA, or NTD), and try that freq. Advanced stuff, but a good skill to have
Fascinating scenario!