travel and rhum

My husband and I go hiking often about 3 to 4 days a week and we've always known the leash laws (we're in California USA). We bring our 20 lb rat terrier with us and today a much larger dog ran up to her aggressively so I picked her up and tried to keep him away. The owner came and struggled to get him to relax so my husband had to help her restrain him. I know a lot of dogs do well off leash but this is just irresponsible in my opinion. When we lived in Oregon we took my 100 lb German Shepherd before he got to old to trail and the same thing happened except it was a small dog. It came up aggressively and my dog was startled, even though he's a gentle giant the owner began to yell at us saying our dog could've hurt hers. Ours was on a leash and he's not at all aggresive. My point is, please leash your dogs. Even if they're not aggresive, there could be another dog out there who is and and isn't wearing a leash. I was scared today for my little munchkin. Please feel free to share your thoughts.