Does it shift OK after it's warmed up? Has it been acting like this all along or is this something new? Might be normal!

By design, upshifts are delayed and the torque converter clutch doesn't lock up when engine coolant temp is below 70C/158F. Helps the vehicle warm up quicker - which is very useful for passing EPA's LA4 emissions test (aka "the city test") but I don't care about all that environmental crap, I just like the way I get heat in a hurry in the winter.

Thank you EPA!