It was a O/W from SEA to BOS - I had to physically recheck my bag in SJU. Also, I had to wait 2 hrs until the USDA people decided to come to work.
I talked with a United agent in the SJU baggage claim when I claimed my bag, she knew what happened. She had a bag tag printed and ready when I went to recheck my bag - I did not have to wait in line.
I do not have a "home base" - I have been traveling for 9 years. Most of my flights are multiple segment O/W flights.