I used the SEA priority lane on May 11 with no problems, but the post above makes it sound as though Frontier may no longer be allowed.

Has anyone contacted Frontier customer service for clarification yet?

On May 9 on my flight DEN-SEA I was questioned about my use of the priority lane at DEN by the TSA agent on the bridge to Terminal A. I didn't know the TSA did this. I thought that part was under airport control and had nothing to do with the TSA. So far, I've only been checked to see if I'd go into the priority lane or the pre check lane at SEA. Without Frontier's name being included on the new sign, this looks like potentially bad news.