If the transmission fluid needs changing, it hasn't ever been done, can that cause a problem in cold weather only, and let it operate normally in warm weather?

My husband's 2000 V70, purchased in August 2003, developed a hesitation as the weather got colder last Fall. It's like the transmission isn't going to shift, and then it finally does with an abnormal force. Once you get up to speed it drives fine. The problem shows up when you accelerate from stops signs, stop lights, etc. On warm days it is hardly noticeable. Have talked to Volvo service (dealer is 2 hours from us) and they said it may need transmission fluid change, car had 40,000 miles on it when we bought it, has 52,000 on it now. It is covered under the extended warranty so I hate to have fluid changed if that isn't the problem. I thought I had read on here at some point that there was something about an update for the computer of this car, but can't find that info again. (Dealer service says they haven't heard of that) Thanks.