Thank you. That is exactly the kind of information I came here for. The Jet Blue agent I spoke with insisted I would need to RE-clear Customs/Immigration at EWR, despite me pointing out that I would have pre-cleared Customs/Immigration in DUB. She was probably thinking "re-clear SECURITY" and mis-spoke. There was confusion because she didn't seem to believe me that Aer Lingus pre-clears in DUB to EWR, BOS, etc. She insisted that you have to clear at your "first port of entry" to the US. I think this Jet Blue agent was just unfamiliar with Aer Lingus' preclearance procedure. Anyway, changing terminals (bus?) and going through Security within 1 hr 45 mins is pushing it.

To reiterate, what prompted me to post here was that Jet Blue called to inform me they had shaved 18 mins off that connection, and it no longer met Minimum Connection Time. Now that I understand changing terminals and clearing Security is involved, I'm surprised Jet Blue considered the original 2 hrs 3 mins to be sufficient.

Getting a refund now and rebooking will be costly. The reason I bought this contorted itinerary is that it was cheap. I used to have status, etc., but now I'm retired and thrifty. (But I have more time.) If I were to rebook through Aer Lingus, the price has now increased, and I would have to rebook at the higher fare. For comparison, I could just as well fly nonstop ATL-BRU on Delta, but Delta charges $1300 for that luxury. Since I have time, I thought I would save $400 and do this contorted itinerary through Aer Lingus and Jet Blue. This is what I get for trying to be thrifty.