'03 H2 - reverse not engaging when firing up after cold night?

[dna]

I live in Calgary, and we have had constant -25 mornings for the last few weeks. About a week ago I noticed that when first firing up the truck in the morning and putting it into reverse, that the truck barely moves back. There was no grinding, instead it was almost like the truck was in neutral but the truck would move back ever so slowly.

After happening everyday, I started testing a few things. First I checked the tranny fluid and it seems full and normal looking but I did smell a faint burnt smell (but I'm not sure either).

I also found that after playing with the shifter (in and out of reverse) that it eventually would 'click' and then I would have full reverse power. After further playing, I found that it isn't based on playing with the shifter, but rather appears to be time related, where after a few minutes of idling the reverse gear clicks in even the first time.

Could this be a sign that the fluid is bad and needs a change, or it is a bigger issue with the trans? Perhaps in the extreme cold, the fluid is not flowing well, so it needs time to warm up? But note that the issue is only with the reverse - all other gears work fine. FYI - I also tried putting it into 4Locked, and it made no different when 1st started in the morning (it again needed those few minutes until reverse engaged).

Any suggestions? I'm thinking of doin a tranny flush, but it is $200 here at the lube shops and if I have a bigger issue then I'd rather save the $200 and get the tranny fixed.

Thanks