Interestingly, I was just online at CMS yesterday checking this. I have a personal NPI, a pending one for the DPC practice (pending for two + years), and an old one from my insurance practice. The personal NPI shows me in PECOS and is the one I give out.
The lab we use says CMS told them my NPI is inactive as of 3/2016 (I opted out 4/1/2016) despite the CMS website showing my personal NPI as active.
I think CMS or their administrative company screw up periodically. We got the same call about six months ago and it went away without any action on our part.