Broad bean disease

I am growing a tall variety of broad bean and once the packet was empty, I decided to collect some of the beans and grow them the following year. As this method of growing the same variety was successful for the first couple of years I noticed the beans now get brown marks on the beans themselves. There appear to be tiny worms/grubs finding their way into the beans but there are no entry holes in the pod. Can anyone advise what this is and if they have the same issue?