The only reason you should worry, is if you are having a problem with a disease or insect damage on the beans.

If you inocculated the soybeans - you will not have to again the second year. If you did not - you should. The soil may not contain enough of the right type bateria to initiate Nitrogen Fixation for soybeans. You can check your existing crop by digging up a plant or two. The roots should look like:

.

Not always are there this many nodules, but - if there are none - then the soil lacks the bacteria - and you need to incoulate at planting next year for best results. Not everone inoculates though - especially where Nitrogen is plentiful.