
I would expect pups to do this if meeting a dominant adult, and certainly when I had my first two dogs of my current breed this was the standard approach for both of them, with the first as she was an only dog and her social skills only developing, and with her daughter because she was a very submissive sort as a pup.
With later dogs they were so well socialised with the number of adults here that they never felt the need to be so placating as they could read other dogs and behave accordingly much better than the first two.
I have found that pups that I have bred who have had the benefit of more than their Mum learn canine manners much better than my first litter who only had Mum.
Have to point out all my dogs are pretty confident individuals, like to keep the peace, but can stick up for themselves if the need arises, so never get bullied.
Oh I have also seen this behaviour on overly bouncy pups, who have learnt that their advances are often met in a negative way so they learn to appease this way.