Short handed collusion?

[DontRaisePlz]

I just played a 5.50 at PS. This guy kept limp/reraising and bet 1k into me every time I checked. The short stack however, often got free blinds (I would estimate 60% of the time he got a walk).

Situation was like this
Hero: 2500-3500ish
Shortstack: 1200-1800ish
Big stack: 7k-9k

My plan was basically avoiding BG and raising every time SS completed his small blind (which he often did, foolishly). I was getting a little peturbed that SB didn't die off though. So I thought BG was far too weak and I started raising him too. It worked at first, then he started limp/raising me but he STILL kept giving SB walks and check/folding flops to him!

When blinds rose to 200/400, it was folded to me on SB. I had JTs and raised allin, about 2200 more to call for BG. He pauses and calls with Q-6s, very uncharacteristically.

After I lose,the very first HU hand, SS raises flop, BG calls, then they went allin with some crap like king high vs. bottom pair.

Does this sound like collusion?