Had to brake hard to avoid a deer….next day drove ~ 15 mi….when I got home left front smoking…wheel was hot!…Took the tire off, removed the caliper…slides are fine, pushed caliper in, it went in easy enough…..plenty of brake fluid in the resovoir…..how can I determine if caliper is ok, and associated brake line?…haven’t driven it yet after looking at it!
can braking hard have caused that problem?

 

Braking hard can cause an issue. It can drive the pistons out past a mark in the caliper which results in difficulty of the piston returning. It may be Ok now but clearly it was stuck. There is a tool you can use to check if the rotor is warped or not. You will also feel it when you stop as a pulsing.

 

Change the rubber brake hose going to the caliper. The inner lining is most likely broken down, and has created a flap that acts like a check valve keeping pressure on the pads.