Gallagher, 18, burst onto the scene with a goal against Yeovil in the FA Cup last month followed by a high profile first professional start against Premier League leaders Arsenal.
"We have noticed a massive difference in him," Dodd told the Daily Echo.
"We were asking him a couple of months ago to get a bit more physical - the problem was we had no one the size of Sam to deal with him.
"Step up into the first team and you've got the likes of Jose (Fonte) who is putting him under pressure. He's had to learn quickly.
"The thing about Sam is that he's a quick leaner and he's adapted.
"The first team players are impressed by what's he's done because he's a level-headed, really nice young man. That's why I think they've taken to him really well.
"You saw when he scored (against Yeovil) that they were all around him, ruffling his hair up and things, so the first team players are taking to him.
"That's a great opportunity for Sam to stay in the squad and try and get more minutes."