The Glasgow Warriors hooker, rewarded for his excellent club form with a first cap, replaced Ewan Ashman on the hour and crossed from Scotland's rolling maul.
"The game went so fast, but it was one of the early touches anyway," Hiddleston told Scotland Rugby News.
"It wasn't a bad thing to come on and score a try on your debut. I'm absolutely buzzing with that as well."
"All the boys did the hard work at the front, and we just kept creeping closer to the line, and I saw the gap, so I just went for it, and luckily enough I managed to get the ball down. I think big credit to the boys at the front of the maul first, and then I was just in a fortunate position to finish it off.
"Obviously you sit there a bit nervous throughout the game, but the boys were playing well and when I got the green light to go on I was actually over the moon and buzzing to get on.
"Mum, dad and sister came across, so yeah, very emotional seeing them after the game, and I'm just buzzing that they could be out here, and I'm very grateful for them coming out and supporting me and supporting all the boys."
Hiddleston's family only booked their flights after he found out on Tuesday that he would be making his debut.
He said: "When I got told I was playing, I shot them a message, and I think they booked the plane pretty quickly after that, so they had a quick turnaround to get things sorted, but they made it here in plenty of time. I told them on Tuesday, so a quick turnaround for them."
On whether they'll travel to South Africa next weekend, Hiddleston added: "No, no, they're back to Dumfries now. I think South Africa is maybe a stretch too far. I'm sure they would have loved to go to that one as well, but, no, they're heading back home to Dumfries."
His family were also in the changing room for his cap presentation after he performed his initiation song.
He added: "Yeah, I sang a song, thankfully everyone joined in, and the changing room had good vibes. I sang Country Roads, so, yeah, it was good.
"They did a cap presentation, and luckily Mum, Dad and my sister were all in the changing room to be there for it. So, it was definitely a lifetime moment."
Hiddleston is now looking forward to facing the Springboks.
"I've been to South Africa before with Glasgow before, and one of the fondest memories I have was when we won the URC out there," he added. "That was a great night to be a part of, so I'm looking forward to getting back.
"I think being in the URC, we go across our two-week tour every season, and it's massive for us.
"So, yeah, we're a bit more used to it now, going over there. I think we've got a good experience being there and know what it's all about.
"But we know it's going to be a big test against South Africa and a big, strong team, so we'll have to put our best foot forward."