Glasgow's World Cup contingent have been eased back into action over the last two games with Hastings and Horne playing a big part in the 50-0 win over Southern Kings at Scotstoun and the 31-7 defeat of Zebre in Parma.
Scotland's disappointing exit at the pool stage is still raw in the memory but Hastings says the return to his daily routine has not been difficult - other than the odd training ground mix-up.
"Sometimes you're still calling Scotland calls in training," said Hastings in the Evening Times.
"But for the most part it's been really enjoyable. I didn't play much when I was away, so I was raring to go, as a few of the boys were.
"It's been very easy to reset. I had the benefit of coming in quite early and playing so I didn't stew on it for too long.
"I had 12 days off and was straight back in. I think the rest of the boys who have come back in now, that'll be firmly behind them now."
The win in Italy marked Glasgow's first back-to-back victories of the season and owed a lot to the partnership of Horne and Hastings.
"I think we're just on the same page a lot of the time," Hastings said of on-field understanding.
"You can see when we swung back on the short side in the first half. A lot of the time it's just about being on the same page as your nine.
"At Glasgow I think I work well with all the nines, but George is a little livewire and he always seems to get himself on the end of tries, which is good to play with."
Hastings took the man-of-the-match award but he was pleased with the overall team performance, particularly given that they had to work hard on an unforgiving, heavy pitch.
"In those conditions, running it is maybe not the best option at times," he said.
"Although I do think our balance between kicking and running was good.
"We ran when it was on, playing what was in front of us was key.
"It wasn't perfect, we struggled at times, but all in all it was a pretty good performance."