I'd normally give you 24 hours to post your logs so everyone else can point out how your data demonstrates something other than what everyone besides you is seeing in the logs. Fortunately I'm on vacation and thus not really all that internet-accessible, so I'm giving you 72 instead. Unfortunately, however, I've seen your post history, and infracted you before for it, so if it turns out you're just making stuff up again (or won't post your logs), I'll be adding an extra infraction point or two, mostly depending on the price of lobster tails on the way home from the great white north.
If you have data, post it, then offer your theories about it. Otherwise I have to clean up a half-page of people telling you you're wrong. Again.
Okay so after a few hours of looking through my logs (30mins straight on test dummy) I've come up with the following conclusion of what's actually happening with heating up/hot streak:
If you have the heating up proc, it takes into account YOUR NEXT SPELL CAST to get hotstreak. What this means is, if you have the heating up proc and are then mid cast fireball, even if you inferno blast after the fireball finishes casting, and even if your inferno blast hits the mob before fireball, the fireball is still the spell being looked at to see if you get a hot streak proc.
Hopefully blizz will change the way heating up/hot streak works to track the next spell that HITS the target instead of the next spell cast, that would result with a lot more hot streaks since you can hit the mob with inferno blast before the fireball hits.
As it stands now though, it is currently tracking your next cast spell, not next hit.