Is My dog too friendly?

I have a rottweiler who is the same way. She never barks at anyone or anything, never bites and is always very friendly with whomever she interacts with. Lately she's been in contact more and more often with our neighbors' dogs, who are aggressive. She has been in, and won, some pretty bad fights but she still treats everyone the same friendly way. My guess is your dog knows how to behave around unfriendly animals and knows how to defend itself. I wouldn't worry.