Slowplaying AA pre-flop in first position!!

PokerStars Game #2420923148: Tournament #11736219, Hold'em No Limit - Level IV (50/100) - 2005/08/25 - 17:10:39 (ET)
Table '11736219 3' Seat #3 is the button
Seat 2: Hardball68 (1835 in chips)
Seat 3: dom462 (1485 in chips)
Seat 6: pocketjohn (9515 in chips)
Seat 7: pez4 (1363 in chips) is sitting out
Seat 8: Trialblazer6 (5262 in chips)
pocketjohn: posts small blind 50
pez4: posts big blind 100
*** HOLE CARDS ***
Dealt to dom462 [Ah Ts]
Trialblazer6: calls 100
Hardball68: folds
dom462: raises 300 to 400
pocketjohn: folds
pez4: folds
Trialblazer6: raises 4862 to 5262 and is all-in
dom462: calls 1085 and is all-in
*** FLOP *** [3s 3c 5s]
*** TURN *** [3s 3c 5s] [7c]
*** RIVER *** [3s 3c 5s 7c] [2h]
*** SHOW DOWN ***
Trialblazer6: shows [As Ad] (two pair, Aces and Threes)
dom462: shows [Ah Ts] (a pair of Threes)
Trialblazer6 collected 3120 from pot
*** SUMMARY ***
Total pot 3120 | Rake 0
Board [3s 3c 5s 7c 2h]
Seat 2: Hardball68 folded before Flop (didn't bet)
Seat 3: dom462 (button) showed [Ah Ts] and lost with a pair of Threes
Seat 6: pocketjohn (small blind) folded before Flop
Seat 7: pez4 (big blind) folded before Flop
Seat 8: Trialblazer6 showed [As Ad] and won (3120) with two pair, Aces and Threes

I recently was playing in this three table sit and go. We were down to 11 players in the whole tournament and I was in tenth position. My chip stack was almost a third of the average stack and my table image was very tight as I had been getting a very cold run of cards so I had started to become a lot more looser with my pre-flop play.
In this hand the player in first position is a fairly aggressive and solid player. He limps in. I raise with my ATo he raises to all-in. Now because he originally limped in first position I never even considered him coming in with any high pocket pair. I took the chance and called. Am I right in my thinking? I have never seen any decent player limp in with AA or high pair in first position. Has anyone else?

Dom