[ns] large delay by Mac802_11 is that right

[anas]

Dear all,

I have encountered a large delay end to end delay
and when I checked the out put file I see some of the packets have a very 
large delay at MAC layer as shown below:

f 202.663960039 _25_ RTR  --- 585 cbr 576 [13a 2b 19 800] ------- [9:1 10:1 
25 30] [17] 7 2
s 358.840523771 _25_ MAC  --- 585 cbr 634 [13a 1e 19 800] ------- [9:1 10:1 
25 30] [17] 7 2
as it appears there is about 150 second at MAC layer

what is the bug here
I used NS2.33 under both Linux and sygwin all of them have the same bug

please help me
best regards
Anas