Sore nipples still...

Stephanie • Naturally delivered our rainbow baby boy in July 2015 💙 and currently expecting our second due in October!
My son is 5 weeks old and we are exclusively BF'ing. My nipples were sore in the beginning and then healed up. The last week though they are sore again when he latches on- not during nursing though. Is this normal or may he have an issue with his latch? Wasn't sure when breastfeeding becomes second nature without any sore nipples!!!