The informant related an Italian proverb learned while spending time in Italy.

Bottglia piccola, vino buono.

It means “small bottle, good wine.” The less literal translation is that good things come in small packages.
The informant said that it is used either when someone is insecure about their height or when someone has given a small gift.

The fact that this is a regional oicotype of a very common phrase in english is interesting. Did the phrase originate in Italy and travel to the states, or did they develop independently? Perhaps it is just a common sentiment and every culture has a way of saying it.