Blame it on the cold? Transmission Problems

[BC69]

During these long dull and freezing winter months, every once in a while I will fire up the Camaro just to run the engine for a while, usually let it warm up in the garage for 15 minutes, then just back it out into the driveway to sit for a while.
Anyway, today I had some problems. My Th350 did not like to get into gear. When I put the car in reverse it would just stay idle and not budge, I thought I was just out of gear and would fiddle with the shifter but it wasnt clicking. Id sit there for about 30 seconds or a bit more and it would lurch into gear for me and I would be off. It also did this when I would shift into Drive 3. Luckily I never had problems with P but that does concern me. The shifter is a little loose and whobbly, but it has never done this before. Could it just be the cold? Or what could be the problem?

This just bugs me because I always seem to spend the fun money on these little gremlins. My exhaust is terminally ill, everytime I look at it its worse, and now this!! Well, better now then during the cruising season.

Any info would help?
Thanks
Tim