my problem

My hu*****and holds H1b for over four years. He travels to Canada (he is also a Canadian PR) almost every week on weekends, and returns before Monday. Every time he stays in Canada less than 30 days, so he never uses a visa to enter the US by driving his own car. But this time on Jan 3, he was stopped at the border, and was asked a H1b visa. Although he was permitted to enter the US at last, but was stamped on the passport and labled "Non-immigrant visa recommended". He asked the border officer if it is required now to get the visa, but the officer was not polite and didn't give an exact answer. It seems the officer knows the 30 days return rules and asked my hu*****and to show proof of not staying over 30 days. My questions are 1. Can my hu*****and shows his pay stub for the proof of not staying over 30 days, or other evidence? 2. If he can prove it, does he still need a visa? Will he have problem entering the US next time without a visa? 3. If my hu*****and applies for a H1b visa, Is there any possibility of getting rejected (he is a Canadian PR)? Thanks a lot!