Testing is a small snapshot of a given day. Kids are more complex than what is captured with testing and can change over time. Gifted or not, all kids should be nurtured and challenged at the appropriate level.
If the test scores don't match what you're seeing in real life AND it is possible financially AND there are doors that retesting could open it might be something to consider. If the scores seem about right and school is working reasonably well and/or scores won't open any doors then I'd think seriously about what would be changed.
Testing a 6 year old is challenging, throw in some E's and it is even more challenging to get an accurate score. I would also add that smart kids can be VERY good at hiding their dyslexia so I wouldn't necessarily rule out the possibility unless you've gone through more extensive testing with a very experienced tester. (I'm assuming that all of your results were from age 6 where reading expectations aren't that high for a smart kid).
We tested our 2e DS (now 10) twice because he wasn't the most cooperative at 6.5 and at that point they said he was probably LD but they'd have to wait a couple years to be sure. The second set of results was very different and more closely matches our experiences with him. I would also caution against the assumption that all gifted kids look like x based on experience with a sibling. We REALLY underestimated DD (now 7) because in many ways she is nothing like DS.
