[ns] help me about MAODV trace file

[=?gbk?B?uvq93A==?=]

 hello all,
    i run the MAODV protocol,but i found a interesting thing:
--s 401.509417279 _0_ AGT  --- 746 cbr 256 [0 0 0 0] ------- [0:0 234881024:-1 32 0] [746] 0 0
--r 401.509417279 _0_ RTR  --- 746 cbr 256 [0 0 0 0] ------- [0:0 234881024:-1 32 0] [746] 0 0
--s 410.543042838 _0_ RTR  --- 746 cbr 276 [0 0 0 0] ------- [0:0 234881024:-1 30 34] [746] 0 0
    why node 0 send the packet 746 after so long time?
    thanks your help