Thanks guys for your observations, but I really dont think its vertigo.
What happens is that it will "blink" in one small part of the sky, and, maybe a minute or so later, "blink" in another part, then a minute later, "blink" in yet another part, and so on...
I have seen this "thing" happen before, a few years ago, in basically the same part of the sky, at approx the same time. I remember reporting it on one of the astro sites (but not IIS), so guess I'll look for the report again.
But I'm pretty sure it's not vertigo.
