Baby Stranger Awareness

My son is a little over 6 months and is in his peak of stranger awareness. In the last month or so he was picky on who he liked holding him but now he won't let anyone hold him other than mom or dad. He's exclusively breastfed and I'm a stay home mom so I feel like I created him to be this way. I go to mom/baby classes hosted by my lactation consultant once a week and she has been warning our group that the stranger awareness happens around 4 months and older and it's completely normal. The moms in the group say enjoy it because one day he will not want to be cuddled and soothed by mom and it's a phase and it will end in a month or two. My husband makes me feel like it's my fault he's like this and my mother in-law who sees him once a week can't hold him more than a minute or two with out him crying and tears running down his face and my husband feels bad for his mom because she has always bragged for being the baby whisperer and he panics with her and I know she doesn't like me taking him while he's crying . . So I don't know what to do, should I leave him in the other persons arms crying and screaming? Or is it just a phase and I should continue to soothe him after? My instinct of course is to soothe him and he is instantly happy and will even smile or giggle with the other person in my arms . . . Any advice or suggestions would be helpful. Thanks!