Floor!!! what's the ruling???

[KC50]

No limit.

Player A bets what appears to be $100 (row of redbirds). Player B asks how much? Player A then "proves the stack" by cutting it into 4 stacks of 5 checks then stacks it back up.

Player B waits about 30 seconds then takes a row of red from his stack and places it next to player A's bet. However he did not release his hand and after about 5 seconds, returns it to his stack and announces "fold".

Is this a call or not and why?

KC