1999 Ford Explorer Steering

Ok, my friend changed my brake pads today.
he is a mechanic. Then he opened up my hood and sprayed some cleaner, he drove the truck and said. Has your steering always bounced like that when you turn? I said NO never.
I drove it and it was hard to turn and the wheel shook a little while turning.
the power steering pump was replaced about 8 months ago. The fluid level is OK
so he tells me that he might have over sprayed some of the cleaner on the belt and it needs to dry. If not to let him know and he would put some dressing on it.

any ideas as to what the heck happened?

I have owned the truck for 5 years and it's never done that.
Thanks.