Is the passage of three asteroids near Earth today just coincidental?
It is just a coincidence, and isn't that uncommon of an occurrence. You can see a list of all such occurrences on this page. Looking at the specific orbital parameters, the orbits are very different. They range from an eccentricity of .2-.5, periods of 349-725 days, and otherwise are just plain different. There are 7 listed in the next week of a similar closeness, so having 3 on a single day isn't particularly uncommon. Much further then a week doesn't really matter because these were only spotted recently, they are all 3 quite small objects. The oldest detection of the 3 was only September 30, and one was only spotted on October 10th.