If it was just the 2 of you in the hand and you were all in, then there was just 1 decision to be made -- call or fold. This can't be collusion, who would you be colluding with?

The same situation with others still in the hand and it's still not collusion, but it IS bad manners and bad form. Personally, I don't like to see people even hint at their cards while the hand is being played by 3+.