Thanks for the replies. I wasn't worried so much about it absorbing into the plastic as I was about 'cross contamination,' since the tubing and impeller likely never fully dry and I don't routinely rinse them off between uses.
Thinking about it, I think I'll pick up another pump anyway. BRS has them for $27 and I should really have a dedicated pump for my QT either way just to prevent accidental disease contamination of my DT.