I was naughty and went 3 months without making any prints or doing any print head nozzle checks.
Did a print head nozzle check a few weeks ago and had a tiny spot missing on the Vivid Magenta channel test pattern. Since it was only a tiny little spot missing in the whole pattern, I thought it was a fluke and printed out another. The pattern was again broken in the same exact spot. Did two more nozzle checks with identical results. Went ahead and did a nozzle cleaning which only took a few minutes. Did another print head nozzle check and all test patterns are now perfect with no breaks.
I am in no way bad mouthing this printer. I absolutely love it and would buy it again. This minor hick-up was self-inflicted.
Just a warning to other P900 owners; although this printer is rumored to be relatively clog resistant, do not expect to go months and months without printing or nozzle checks. A clog could develop.