Coolant temp spikes
 

I bought a 2013 SLT 3.6L with 24K miles on it 14 months ago and love it. I've put an additional 8K mi on it and recently I've noticed the temperature gauge has been spiking to 3/4 of the way and fluctuating between 212° and 228° . No engine light but isn't this a little high? This wasn't the case until recently. I changed the radiator cap after checking the coolant level which was full. Hoses seem a little soft to me. I've been told not to do too much to it because it's still under warranty. Any suggestions?