<human>: Hello all, I'll try to make this as concise as possible:

Draco is my 60 lb lab mix.  Loves everything - dogs, people, kids, whatever.  He's confident, easy going, energetic and can play with any dog.  He is 1.9 years, and I've had him for 10 months now (he came from a pound).  

We always go to the dog park.  Tonight a one year old Mastiff was there, that he's seen before.  And every time before he goes crazy and harasses this poor mastiff to death.  Hackles up, maniacal barking (somewhat normal bark but rapid fire, nonstop, intense) and circling.  He doesn't attack the dog, but it's like he's really excited to see this dog and it's constant harassment.  The mastiff just stands there with his tale wagging looking like he doesn't know what to make of it (and he's like twice the size of my dog, so Draco really looks stupid).  Now, Draco was attacked like twice when we first started going to the dog park in December of 2011 by a Cane Corso (eventually cane corso was banned).  

I feel that I can read Draco very well, but this has me puzzled.  He's not attacking the dog whatsoever, but it's obviously bullying and the mastiff obviously sets him off.  Other regulars were surprised by Draco's behavior.  It just seems like such a long time gap, but: Could his behavior towards the Mastiff be because of him being attacked like ten months prior by a big ass dog?  Or any other thoughts aside from dominance (clearly not a dominance issue)?

Can you summarize the given text in a few sentences?
<bot>: Friendly lab mix attacked by cane corso ten months prior, now showing aggression towards mastiff.  Correlation or other cause?