Scared of Dogs?

Had a strange thing happen today, very unlike Loki. We saw a man with four dogs walking towards us on the field. Three of them were on leads (and barking at Loki) and one of them was off the lead, walking to us. The man shouted over that the one off the lead is friendly, so I let them sniff. Loki was stood there, body lowered, very still, etc. He had a bit of a sniff, and then the other dog walked on and that was it. I found it odd, but I put it down to the other dogs making him cautious. Then later on, we saw this woman walking a very small dog off the lead. The dog came over to Loki and, again, Loki had his body lowered and was very still but had a little sniff. The dog growled at him (not Loki's fault, the woman said he gets a bit grumpy) and then walked on. I understand being cautious about big dogs, but this dog was half the size of Loki. I could just say it was submission, but I don't know, it looked quite a bit like he was scared. Plus, he usually sniffs for a bit, not being submissive nor dominant, just normal I'd say, and then tries to play. So submissive or not, it's out of character for him. He hasn't had any bad experiences; in his whole life, he's been growled at about four times, and two dogs have tried to attack him (but didn't manage to even touch him), and none of these experiences were recent, so there's nothing to suddenly scare him. So I wonder why he seems to be like this now, especially since he still wanted to actually meet the dogs.

Oh, and just to add, it's worrying me that he might be developing some sort of fear aggression, for seemingly no reason. I remember my mum saying he growled at another Staff a while back, but I wasn't there so I don't know if it was play or frustration as opposed to aggression. But today, both times he met the dogs, when they were done sniffing and they were walking past them, he seemed to try to jump at them. He does this as part of playing, so it could simply be him wanting to play, but it seems odd that he looks scared, and then when they walk away, he wants to play. I'm just wondering if it's not just play. It happened really quickly, I couldn't really notice any of his body language to clue me in on what it might be. It's worrying though.

Hi Tara, Loki is very young and still learning social skills around other dogs, because he is young he will show signs of submission toward an older dog whether a Rottie or Yorkie. Nothing to worry about, he sounds like a very polite little dog.