Now that you have a better understanding of why she bared her teeth, you can work with her to change how she feels in that situation.
Yes, baring her teeth is a warning. But she shouldn't need to warn you simply because you are standing over her while she eats. That reaction is inappropriate for the situation (if that is all you were doing at the time).
Growling is different. Some dogs are vocal. Some have play growls or happy talk. But there is always a difference between "I'm having fun" or "I'm happy" and "I'm scared/stressed". Knowing the difference in those vocalizations is very important.
When the dog gives the "I'm scared/stressed" vocalization, you need to figure out why and determine if it is an appropriate reaction. If they vocalize because there is someone sneaking around the RV, then that's appropriate. If they vocalize because you put a leash on them, then that's inappropriate. In that situation, you have to teach them that the leash is not something to be afraid of.