After routing, the 1/2 inch bit was frozen pretty good in the collet. Actually had to use pliers to twist it loose. The collet had not bottomed out, nor was excessively tight. Upon inspection, neither the collet nor the bit were warped or damaged in any way to cause a freeze (at least by eyeball exam).
Should one put a bit of white grease or machine oil on the bit during insertion? I hesitate, since drips might stain the wood. I'm not even sure this would help the situation.
Thanks for any info, Chuck