Non-sense - perfectly likely and more so, in my opinion, than someone deciding to reverse the order despite their being two previous examples with the opposite wording.
Fair enough. As I mentioned in the matthean priority thread, Mark's pericope order is always supported by either Matthew or Luke.
Some periscopes in Mark seem to be a conflation of the other two's versions. So for the women at the tomb pericope: Matt and Luke write "he is not here, he has risen". Mark writes, "He has risen, he is not here". When placed in the context of "you are looking for Jesus, who was crucified", and "why do you look for the living among the dead?" it is clear that Matthew and Luke flow smoothly, as they say, "you are looking for....he is not here". Mark's "you are looking for....he has risen" is less smooth, since "he has risen" is not related to where Jesus is. This suggests that Mark has taken the part of the message to the disciples ("tell them he has risen") from Matthew and put it in the slightly awkward position, ahead of, "he is not here".
If Mark were using Matthew and Luke, we would expect this kind of disjointedness. And if Matthew was writing directly from an eyewitness, he would compose his sentences so that the ideas flowed smoothly, as here.