Piston Pete

A couple of friends and I had some fun last night, driving spiritedly and all. Well, throughout the night and on the way home I was getting the worst boost pattern yet, a 5-5-0, 5-5-5, 7-5-5 and all variations in between that. Then this morning after cold start and proper warm up (10 minutes of no boost) I had 10-5-10. 10-5-10 is normal for me and I'm happy with that right now, but how come my boost is intermittant like that? Could it be heat expanding things in the engine and creating a boost leak?

-Anthony