Yep, just some selling (and an equal amount of buying, of course), with not the slightest indication of manipulation. Some people seem to think that almost any time a stock drops it's being manipulated, but invariably they can't quite explain how it's being done, or for what logical purpose.
That's not to say that manipulation of thinly traded stocks never occurs -- it's quite common, no matter where the stock is traded. But it's not what we're seeing today with IMSC.