answer

[ramyarak]

No: HPFGUIDX 60509

Fred and George never noticed Peter Pettigrew on the marauder's map, 
because I think that the person viewing the map should know the 
people/animagi/animals appearing on the map very well and those 
people should have a direct impact on the future of the person 
viewing it. Because, otherwise the map would get too cluttered-up. 

For example, Harry sees Dumbledore pacing his study and Mrs.Norris, 
because he would not want to get caught by either of them while 
sneaking out to Hogsmeade.

"Ramyarak"