Nah, it'll be fine. If you let it do it many times and it stayed at that temp for a long time each time, it may have done a bit of damage, but in your situation, I don't think you did much, if any, harm at all. Honestly, the voltage may have done more damage than the temps ever could, since GPU's are very sensitive to even relatively small voltage increases, but you lowered it back down, so I'd say you're good.