bubble tip anem losing tentacles

Had this green bta for 2 or 3 weeks now. Has stayed in the same place I put it and has been eating and looking healthy. I just found one of it's bubbles in the intake of a pump and pulled it out. It's still inflated. Any reason it would drop a bubble? The pics were taken 5 minutes ago, just after feeding and 1 of the lost bubble in a container.

It's color still looks OK .Mine lost a few over the years I have had it. Not to worry if it still looks healthy