hi, just read tour thread and ihave to say that on those circumsanses, while nobody was raising and you got to see a pretty chip flop with you jack and your "wipeass" kicker. that happenned (i surpose) because, he didnt raise preflop!
So the the jack came on the flop... its not like you had pocket jacks or J 10 in your hands! it is a reasonabale check that you did, waiting to see hes action.
I wouldnt have problem of folding the J 4 right away.. i tell you that.
he had outs to beat you, your lonely jack didnt survive the attack... but thats the kind of the decisions that the big stackers should make and the low stackers have to gamble.
Cheers