There have been quite a number of issues with the PT145 and light primer strikes. I wonder if this is a design issue or weak firing pin springs in the Millennium Pro series. It would be great to hear the thoughts of other Millennium Pro owners out there.
I get occasional light strikes on my PT111 Pro also but only when using range reloads. However, I think this comes down to a batch of low quality and hard primers the range reloader used recently. Previous batches of reloads fired flawlessly. I have had no problems with factory loads and premium factory JHPs as well. Cleaning issues could also be the culprit. Maybe there was some accumulation of dirt or dried up lubricant in the firing pin channel after the last clean and lube done on your PT145. Best try it again after a good clean.