Collusion, smart poker or 'no friends' - Cash game play

So you are at your regular cash game sitting next to what else, a regular, and you are both hitting the deck hard today both in play and great hole cards. Your 'friend' leans over and says that "normally I ... we ... should go after each other but let's lay low today and keep running this table over and avoid hands with each other". I say "Sometimes that is unavoidable" and kind of knod my head 'in agreement'. Over the course of the next 3 or 4 orbits this guy is opening pots higher than normal (being very aggresive all the time anyway) and I, being on his left, am feeling kind of left out of this 'arrangement' ... not that I was getting cards anymore anyway.

So I finally get in a hand and flop a double-belly-buster straight draw, rainbow board. SB leads out and this guy min-raises. I start to look at the Button and SB and then I start getting this guy bumping me in the leg under the table ... more than likely in a way that some at the table would have had to see it ... multiple times!! This is (must be) my signal to fold and let him have the pot ... right. Or is it? I have him covered by a small amount and I am close to being priced in as I sense the SB will call, possibly the Button as well ... and implied odds are screaming at me in my head that I could have the largest score I have ever had if I felt him. But then comes a second round of leg tapping ... so I ask the SB what he has in his stack trying not to insta-fold to the obvious activity happening under the table.

I end up folding as does the Button with the SB calling as I thought he would. The Turn is a blank ... SB bets out, my 'friend' goes all-in, SB calls and I would have hit the high end of the straight on the River. SB shows 2-pair ... 'friend' shows a flopped low-end straight.

Now granted I certainly would not have called the Turn all-in ... and it's possible that the SB goes all-in on the Flop as well, which I don't call either. But the dilemma here is how do you handle this situation as a whole? Is there a long-term 'relationship' between regulars at the table going after the fish money and not each other? I am interested in your thoughts ... I certainly would have called the all-in if I had called the Flop and made my hand on the Turn so there is no question there. The issue is the influence I allowed by the tapping leg ...

As it turns out the 'Poker Gods' were looking out for me later and I still cashed out a top 5 cash session for me ... so if I had called, the cards muck different and all the future hands never happen. Is this collusion? Smart poker to avoid losing one of your largest scores yet? Or are there no friends at the poker table? Options ... Such is poker ... I await your comments.