Transmission long to engage, stuck caliper piston

WHen the car has not been in use for some time (several days) , the FWD clutch takes as long as 10-15 seconds to engage at first start....then afterwards, all will be normal. I think this has been discussed in the past, just looking for comments on that.
And yesterday, (car had been still for 10 days...)...this time no delay with transmission, but got stuck calliper on left front....I removed the tire and got it somewhat unstuck,(just a quick "save" for the trip) able to have the piston move back and forth about 1/8 of an inch..really "hard".. will go deeper into this to-day or tomorrow....

OK..1st and 2nd work on sprag cluth when the lever is on Drive or OD. I noticed the engagement is immediate if I choose the 1st or 2nd position on the shift lever because it applies 3rd clutch and 1/2 band that are not engaged in Drive/OD mode. .
www.avigex.ca/xport/transmissionranges.jpg
THis would indicate the sprag clutch is slow to engage....but is OK after a little time.