I believe this came up before long long ago and it was associated with the molding process. That being said I would look it over close with good light and magnification and watch it close. As I recall it was nothing to worry about and of course worrying accomplishes nothing but never hurts to keep an eye on it.
In Memory of Paul "Dietrich" Stines.
Dad: Say something nice to your cousin Shirley
Dietrich: For a fat girl you sure don't sweat much.
Cue sound of Head slap.
RIP Muggsy & TMan
"If you are a warrior legally authorized to carry a weapon and you step outside without that weapon, then you become a sheep, pretending that JOCKO will not come today."