Sippy cup mold complaints

HOUSTON (FOX 26) - A father is sharing this warning online. He discovered mold after his son was sick. The pictures posted online show the problem in the non-spill valve of a Tommee tippee sippy cup.  The company that makes the cups says it is developing a see-through valve but says the mold problems are most likely caused by parents putting drinks that aren't recommended like formula, or warm drinks in the sippy cups.