Sirius' motorcycle

[Brian]

No: HPFGUIDX 3315

Hello everyone,
   I was listening to PoA in the car this morning and something 
caught my ear.  Hagrid says that he was sent to James and Lily's 
house to retrieve Harry and, while he was there, Sirius arrived on 
his flying motorcycle.  The statement I can't quite figure out is 
that Sirius gives his bike to Hagrid and tells him that he's not 
going to need it anymore.  Why didn't he want his bike?  It seems to 
me that it was more than just wanting Harry to get to AD as soon as 
possible.  Since he was innocent and had no reason at the time to 
believe he would be framed for the murders, wouldn't he still want 
it?  On top of this, Hagrid mentions how much he knew Sirius loved 
that bike.  Now I remember in SS/PS that Hagrid tells AD that he has 
to get the bike back to Sirius.  I'm assuming he didn't feel right 
keeping the bike regardless of Sirius' words about not wanting it.
   Any thoughts?