keg this batch?!

I'm going to keg two batches tonight for the first time. I've got an ESB and an Irish stout ready to go. Two montgs ago, when the stout was new in primary, it got infected and things got pretty funky. I let it relax for awhile and everything seemed fine and it actually tasted pretty good. I noticed earlier this week that there are some light chalky looking rings around the neck of the secondary. the surface of the beer looks totally normal. Has the infection returned? should I keg this batch? I dont want to get off on the wrong foot by infecting the first two batches in my keggerator, but this stout seems like it might be ok. help!

well, keg racking takes all of 5 minutes...its not like wasting an hour or more bottling 2 cases of longnecks.

I'd keg it second, to avoid potential cross contamination. and avoid disturbing the chalky stuff in the carboy neck.