spotlights outlining two large cloud formations. Blinked on and off in syncrony. At least 30 of them

It is wierd to recall this because at the time it starteld me and I was just in a hurry to get out of the area. I don't beleive it was little green men or anything supernatural, but I would like to know what it was..as in maybe it was a military maneuver?
I was traveling late in the day to Bozeman Montana from Great Falls, Montana. I was driving my car alone on a single lane highway and upon ariving on the crest of a hill top I could see that for many many miles no other cars or houses were present. I felt quite alone just then. 
Then above me I saw two large cloud formations directly above the road that were outlined by many dozens of spot lights in a near perfect distance from one another surrounding both clouds. It looked as if helocopters were hiding behind the clouds.  The moon light was just so that I could see the clouds even before the spot lights came on. 
Then just as suddenly they blinked off while I continued on my way frieghtened by what I had seen. I have been curious for more than 22 years, but never thought that strongly about those lights. 
Can you tell me if anyone else may have seen something like this?
Witness indicates that date is approximate.  PD