Not at all! In fact, we see it as a sign of respect.
It will also help you with the heat! these things are designed for the hellish weather in this desert.
One thing to remember, be sure to use the right name in the right place, for some reason it has many names depending on the place and people might not understand it. The name "Thobe" in the UAE for example is used for ladies dressdresses, while Kandura anywhere else but the UAE sounds funny.
Finally, thobe is not related to Islam. It's an ancient dress for the Arabs in the peninsula, way before Islam. However, it's also used byduring my visits to many non Arab Muslimscountries with Muslim population, I noticed that it's used occasionally, especially when attending Friday prayers.