Better check your plumbing because I hate to say it, PEX is everywhere and it's yet to be shown if there are long term effects on having plastic plumbing everywhere. My kitchen water tastes like plastic all the time.
PEX is fine. Water that sat in a PEX pipe is chemically indistinguishable from water held in a test tube, unlike what happens with water in PVC piping. Another indicator of fine-ness is that PE and PP tubing is used extensively in chemical process plants where high purity is required.
