I noted on Twitter a report that General Michael Flynn had stated there was strategic warning, oddly few have noted this.

From his interview with NPR, a good section was on Mr Snowden. It starts with:
I think for easily seven to ten days leading up to the Russian troops as we see them now in Crimea, we were providing very solid reporting on what I would describe as just strategic warning, where we move from one level of sort of a condition of warning, which I would just describe for the audience as sort of moderate, to one where we believe things are imminent. And we did that about a week prior to the events that unfolded really last Friday.
Shortly afterwards:
Well, I mean obviously the things that we' re watching in the Crimea, some of the naval activities, you know, up around the key bases — we saw, you know, we see some of what has been referred to as an exercise inside of Russia and we are paying very close attention to any additional activities of some of their key military forces that they do have, particularly in the southern military district that is in that region that we are all concerned about right now. So — there is a lot of activity. What we are trying to pay attention to is: are they being true to their word about it's an exercise versus something else.
Link:http://www.npr.org/2014/03/07/287037...-michael-flynn

One of the odder, possible signs I spotted was the arrival in the Black Sea of a Russian Navy amphibious transport - from the Baltic Fleet - which has now unloaded a number of heavy trucks etc.