Ok this is probably a stupid question but here goes. I filled about 8 growlers today for gifts. The beer was forced carbed in a keg. I normally try to cap on foam but these filled so nicely i hardly got any foam so most of the growlers are filled to the top with very little head space. Will the lack of head space be an issue? Since the beer was force carbed in the keg i'm hoping not but i don't want them to explode.