Power steering when hot hot hot
 

I went to visit my folks in Green Bay, top down and 90+ degrees. From Chicago over 200 miles. Took my dad out for some car shopping for him so I probably put another 100 miles on, Still 90+ degrees. Toward the end of the day of crawling around carlots (unfortunately they wouldn't let me climb the Land Rover trail) my steering made some weird pulsing/minor binding can't print bacause I can't write it, noises as I was turning a tighter corner or turned quickly will idling around the lots. Didn't hear or feel it while on the road. The next morning it was and on the drive home it was fine. It was so hot, I had to use a rag to open the hood. Do you think it was boiling the fluid thus being a one time thing or something starting to fail? I have 4,000 mile on my warranty left and they replace a leaking steering box (twice). Any thoughts?