Ok, so I was practicing ATTI flying today to make sure I was prepared in the event of lost GPS. I was only flying about 18-24" inches off the ground (in ground effect) at low low speeds when I bumped into a tree, striking two of the props. I cleaned the props with a damp cloth to get the sap off, and checked the leading edges with my eyes and fingertips, and found no detectable aberrations. If this was a Cessna, it would be off to the prop shop, but the is not a Cessna. Are they safe to fly?