Currently, according to Yahoo, bid/ask is 17.01/17.89. When spread is this high, neither putative buyer or seller will see trade executed: instead, someone else may buy at 17.0101 or sell at 17.8899. It should not be this way, but it is what I have noticed, most of the time, when spreads are large. Someone is making money at expense of small investor. I have no plans to buy or sell shares today.
Looks as if your warning is still valid, and I would add that it is absolutely insane to put in a market order at the open for this stock. If you do you will wind up paying over 12 for a stock that will soon trade a 10 1/2 again.