Is the insta-check a low limit online tell?

[shark6]

I've been playing the $0.25 BB at Stars.

If 3 or 4 other people see limp in to see flop, then all insta-check (within say 0.5 sec) to me on the button I bet the pot everytime after waiting 8-10 seconds myself. 90% of the time I pick up the pot right there.

In fact, I often find this is the case on later streets as well.

How much do other people use the length of time it takes an opponent to make a decision as the basis for how to play a hand?