Ilsa's got about 5-6 of these - most are very small. They're nothing to worry about, just keep an eye on them. If they get bigger or impede movement, have them checked again.
Vets don't liek removing them because they're basically just ugly - leaving them there isn't a health risk, and it's more of a bother to put the dog under anesthesia, remove the lipoma and have to deal with recovery time than to just leave them be.