Gap concept

I've 1200 chips, the blinds are 200 chips, I'm UTG with 44. I reckon this is a good position to push and pick up the blinds. The table has been very tight. I'm hoping that everyone will fold. However, BB calls with A8. I'm not quite sure what BB put me on. Calling with A8 in this position is a bad move. What can it be beating? A7, A6? Would UTG push with that. Possibly. UTG could have a strong ace. eg AQ. BB would have been knackered then.

On the other hand, if I'd have had A8, I might have made the same move. In summary, I would push with 44 or A8, but wouldn't call with them in a raised pot. This is known as the gap concept.

Table "STT 3453674 - 1" Seat 5 is the button.
Seat 2: Prince022 (2462 in chips)
Seat 4: Garyholli (1303 in chips)
Seat 5: papillon (2535 in chips)
Seat 7: Pedro28 (555 in chips)
Seat 9: Thepindro (1955 in chips)
Seat 10: RumTiddle (1190 in chips)
Pedro28: posts small blind 100
Thepindro: posts big blind 200
----- HOLE CARDS -----
dealt to RumTiddle [4d 4c]
RumTiddle: raises to 700
Prince022: folds
Garyholli: folds
papillon: folds
Pedro28: folds
Thepindro: calls 500
----- FLOP ----- [6c Ah Js]
Thepindro: bets 1255 and is all-in
RumTiddle: is all-in 490
Returned uncalled bets 765 to Thepindro
----- TURN ----- [6c Ah Js][Th]
----- RIVER ----- [6c Ah Js Th][9h]
----- SHOW DOWN -----
Thepindro: shows [8d Ad] (A Pair of Aces, Jack high)
RumTiddle: shows [4d 4c] (A Pair of Fours, Ace high)
Thepindro collects 2480 from Main pot
----- SUMMARY -----
Total pot 2480 Main pot 2480 Rake 0
Board [6c Ah Js Th 9h]
Seat 2: Prince022 folded before Flop (didn't bet)
Seat 4: Garyholli folded before Flop (didn't bet)
Seat 5: papillon (button) folded before Flop (didn't bet)
Seat 7: Pedro28 (small blind) folded before Flop (didn't bet)
Seat 9: Thepindro (big blind) showed [8d Ad] and won (2480) with A Pair of Aces, Jack high
Seat 10: RumTiddle showed [4d 4c] and lost