Bad move or bad timing?

[Indestructable]

In an mtt final where only first place matters. I am down to last 36 and in 12th place having slipped a bit.
I have 4000 chips, i am big blind and get
 
there are a few callers and I check. The flop is
    

I slow play (was i wrong here?) and I check.
Player A with 6500 chips makes a small bet of 200 and player B with 7000 chips calls and I also call.
The turn is
 
I check again.
Player A bets 400 and Player B immediately calls as do I.
The river was
 
So we have no flush or straight possibilities. I had convinced myself that one player may have an 8 and the other an ace.
I bet 500 and I am raised to 1500 by player A, Player B goes all in.
I call and so does Player A. I was right that Player B had an ace, but Player A revealed
 
I had thought I was trapping here and looking forward to a good return. Only to find i was the prey and well and truly stuffed.
Up to this point I had played fairly well and quite patiently, but i also knew that it was a winner takes all situation and no point just looking for a final table pay out.
Any advice or thoughts on how I played this. I guess there are two questions, should i have bet differently early on, and should i have gone all in or folded?

[Nem]

In an mtt final where only first place matters. I am down to last 36 and in 12th place having slipped a bit.
I have 4000 chips, i am big blind and get
 
there are a few callers and I check. The flop is
    

I slow play (was i wrong here?) and I check.
Player A with 6500 chips makes a small bet of 200 and player B with 7000 chips calls and I also call.
The turn is
 
I check again.
Player A bets 400 and Player B immediately calls as do I.
The river was
 
So we have no flush or straight possibilities. I had convinced myself that one player may have an 8 and the other an ace.
I bet 500 and I am raised to 1500 by player A, Player B goes all in.
I call and so does Player A. I was right that Player B had an ace, but Player A revealed
 
I had thought I was trapping here and looking forward to a good return. Only to find i was the prey and well and truly stuffed.
Up to this point I had played fairly well and quite patiently, but i also knew that it was a winner takes all situation and no point just looking for a final table pay out.
Any advice or thoughts on how I played this. I guess there are two questions, should i have bet differently early on, and should i have gone all in or folded?

You made a blocker bet (meaning if it is raised you fold) but you didn't fold. Once your bet is re-raised in this scenario, you HAVE to fold.

[temp0r]

exact same thing happened to me yesterday. it's simply unavoidable. but trust me it's worse when it's PL cash and you DON'T slow play it and lose over $100 on it.

[NoflopsHomer]

You need to raise on the turn, i think. Remember any Q9 or higher is also beating you. The raise will tell you where you stand in regards to a high set of trips or better.

[Indestructable]

I think my main criticism of how I played it was that I was so confident of winning the hnad that I was blind to the possibility of losing it. I should have at the very least paused and thought it through more. I guess I live and learn.