Yes, I agree with you, it's a good possibility. You say about the poor quality of the glass: perhaps, the glass is not the same, you can see that on the pic, but it does not seem of poor quality but different. Yes there are bubbles, I believed it was little holes to hold the cane because few holes are in the same places, but after your note, I see that there are bubbles elsewhere around the top of the bead.
thanks!