Are you rolling your Civita Day Pack into a giant spliff and lighting it up?  I would normally wonder why anyone would give your day pack "questionable looks and comments", but then you mentioned Pennsylvania.  Having lived there for a long time, it explains a lot as it's like hillbilly country between Philadelphia and Pittsburgh so it wouldn't surprise me that some yahoo would make a dumb comment about a fabric.
No one in Ireland will care or look twice even if you wrapped yourself from head to toe in hemp.  If it makes you feel better, my family lives in a small village in Western Ireland and I've seen some of the girls wearing hemp infinity scarves and pants to kick around in during the summer.