That is not so unusual, it takes a lot to keep a 10 incher hard. Back in the Gaiety/Stella days, I hired 'Bam Bam' who had a similar endowment. He just couldn't keep it hard. It thought it was ME. But later, I saw him in a porn video clip and he had the same issue.
By the way, the plural of 'inch' is 'inches'. Thank you.