Probably not an issue Tbh, there will be a more dense CO2 blanket on top that should keep it mostly insulated from O2 and any additional CO2 production should vent any O2 introduced I think.I was thinking about the dry hop.
Is it the case that even lifting the lid and dropping them in followed by purging headspace with CO2 would result in sufficient oxygen to cause a problem? Considering any oxygen in the transfer line when transferring would be an issie, I suppose I should avoid removing the lid at all for the dry hop.
I (probably mistakenly now I re-read it) assumed you were pressure fermenting and then pressure transferring, in which case opening up to introduce your hops isn't really an option.